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OceanStor V3 Series

V300R006

HyperMetro Feature Guide for Block

Issue 05

Date 2018-01-30

HUAWEI TECHNOLOGIES CO., LTD.

No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders.

Notice

The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd.

Address: Huawei Industrial Base

Bantian, Longgang Shenzhen 518129 People's Republic of China

Website: http://e.huawei.com

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DANGER

WARNING

OceanStor V3 Series HyperMetro Feature Guide for Block

Purpose

This document describes the working principle and application scenarios of the HyperMetro feature. It also explains how to configure and manage the feature.

The following table lists the product models applicable to this document.

About This Document

Product Series

OceanStor 2000 V3 series OceanStor 2600 V3

OceanStor 5000 V3 series OceanStor 5300 V3, 5500 V3, 5600 V3, and

OceanStor 6000 V3 series OceanStor 6800 V3

OceanStor 18000 V3 series OceanStor 18500 V3 and 18800 V3

Intended Audience

This document is intended for:

l Technical support engineers l Maintenance engineers

Symbol Conventions

Product Model

5800 V3

The symbols that may be found in this document are defined as follows.

Symbol

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Description

Indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.

Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.

NOTE

OceanStor V3 Series HyperMetro Feature Guide for Block

Symbol Description

About This Document

Indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.

Indicates a potentially hazardous situation which, if not avoided, could result in equipment damage, data loss, performance deterioration, or unanticipated results.

NOTICE is used to address practices not related to personal injury.

Calls attention to important information, best practices and tips.

NOTE is used to address information not related to personal injury, equipment damage, and environment deterioration.

Change History

Changes between document issues are cumulative. The latest document issue contains all the changes in earlier issues.

Issue 05 (2018-01-30)

This is the fifth official release.

Optimized descriptions about section Impact and Restrictions.

Added the following FAQ: How Can I Use OVA Templates to Quickly Deploy Virtual

Quorum Servers?

Issue 04 (2017-11-30)

This is the fourth official release.

Added the description about arbitration mechanism or configuration operations when configuring two quorum servers.

Issue 03 (2017-08-30)

This is the third official release.

Synchronizes some software interface changes.

Issue 02 (2017-06-01)

This is the second official release.

Optimized descriptions about section Impact and Restrictions.

Synchronizes some software interface changes.

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iii

OceanStor V3 Series HyperMetro Feature Guide for Block

Issue 01 (2017-11-30)

This issue is the first official release.

About This Document

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OceanStor V3 Series HyperMetro Feature Guide for Block Contents

About This Document.....................................................................................................................ii

1 Feature Description....................................................................................................................... 1

1.1 Overview........................................................................................................................................................................ 1

1.2 License Requirements and Compatible Products........................................................................................................... 2

1.3 Working Principle........................................................................................................................................................... 3

1.3.1 Basic Concepts............................................................................................................................................................ 3

1.3.2 HyperMetro Solution Overview.................................................................................................................................. 5

1.3.3 Arbitration Mechanism................................................................................................................................................9

1.3.4 HyperMetro I/O Processing Mechanism................................................................................................................... 17

1.3.5 Functions of a HyperMetro Consistency Group........................................................................................................19

1.4 Impact and Restrictions................................................................................................................................................ 22

1.5 Application Scenarios...................................................................................................................................................24

2 Planning........................................................................................................................................ 27

3 Installation.................................................................................................................................... 28

3.1 Installation Process....................................................................................................................................................... 29

3.2 Preparations for Installation..........................................................................................................................................29

3.2.1 Preparing Tools, Meters, and Documentation........................................................................................................... 30

3.2.2 Quick checklist for the installation environment.......................................................................................................32

3.3 Device Installation........................................................................................................................................................38

3.4 Cable Connection......................................................................................................................................................... 41

3.5 Power-on.......................................................................................................................................................................46

3.6 Storage Array Initialization.......................................................................................................................................... 49

3.7 Multipathing Software Installation...............................................................................................................................49

3.7.1 UltraPath Software Installation................................................................................................................................. 49

3.7.2 Third-party Multipathing Software Installation........................................................................................................ 49

3.8 Arbitration Software Installation.................................................................................................................................. 50

4 Configuration............................................................................................................................... 53

4.1 Configuration Process...................................................................................................................................................54

4.2 Configuration Preparations...........................................................................................................................................56

4.3 Configuring Switch.......................................................................................................................................................57

4.4 Configure Quorum Server Software.............................................................................................................................57

4.4.1 Configuring the Arbitration Software (SUSE).......................................................................................................... 57

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4.4.2 Configuring the Arbitration Software (Red Hat/Red Flag/NeoKylin/CentOS)........................................................ 62

4.4.3 Configuring the Arbitration Software (Ubuntu)........................................................................................................68

4.5 Configuring Basic Storage Services............................................................................................................................. 73

4.6 Creating SAN HyperMetro...........................................................................................................................................74

4.6.1 Checking the License File......................................................................................................................................... 75

4.6.2 Adding a Remote Device...........................................................................................................................................76

4.6.3 Creating a Quorum Server.........................................................................................................................................79

4.6.4 Creating a HyperMetro Domain................................................................................................................................ 81

4.6.5 Creating a HyperMetro Pair...................................................................................................................................... 82

4.6.6 Creating a HyperMetro Consistency Group.............................................................................................................. 88

4.7 Configure a Multipathing Policy for Host....................................................................................................................91

4.7.1 Configuring a UltraPath Policy for Host................................................................................................................... 92

4.7.2 (Optional) Configuring a Third-party Multipathing Policy for Host........................................................................ 97

4.8 Verifying the Configuration........................................................................................................................................100

5 Management............................................................................................................................... 101

5.1 Managing a HyperMetro Pair..................................................................................................................................... 101

5.1.1 Viewing HyperMetro Pair Information................................................................................................................... 102

5.1.2 Modifying HyperMetro Pair Properties...................................................................................................................107

5.1.3 Synchronizing a HyperMetro Pair...........................................................................................................................109

5.1.4 Suspending a HyperMetro Pair................................................................................................................................110

5.1.5 Switching the Preferred Site for a HyperMetro.......................................................................................................110

5.1.6 Forcibly Enabling a HyperMetro Pair......................................................................................................................111

5.1.7 Deleting a HyperMetro Pair.....................................................................................................................................112

5.1.8 Expanding the Capacity of a HyperMetro LUN......................................................................................................113

5.2 Managing HyperMetro Domains................................................................................................................................114

5.2.1 Viewing HyperMetro Domain Information.............................................................................................................115

5.2.2 Modifying a HyperMetro Domain...........................................................................................................................115

5.2.3 Deleting a HyperMetro Domain.............................................................................................................................. 116

5.3 Managing Quorum Servers.........................................................................................................................................117

5.3.1 Viewing Quorum Server Information......................................................................................................................117

5.3.2 Modifying Quorum Server Information.................................................................................................................. 118

5.3.3 Adding a Link.......................................................................................................................................................... 118

5.3.4 Removing a Link..................................................................................................................................................... 119

5.3.5 Removing a Quorum Server.................................................................................................................................... 119

5.3.6 Uninstalling the Arbitration Software..................................................................................................................... 120

5.4 Managing a HyperMetro Consistency Group.............................................................................................................121

5.4.1 Viewing the HyperMetro Consistency Group Information.....................................................................................121

5.4.2 Modifying the Properties of a HyperMetro Consistency Group............................................................................. 124

5.4.3 Synchronizing a HyperMetro Consistency Group...................................................................................................127

5.4.4 Pausing a HyperMetro Consistency Group............................................................................................................. 128

5.4.5 Switching the Prior/Non-prior for a HyperMetro Consistency Group.................................................................... 128

5.4.6 Starting a HyperMetro Consistency Group Forcibly...............................................................................................129

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5.4.7 Adding a HyperMetro Pair...................................................................................................................................... 130

5.4.8 Remove HyperMetro Pair........................................................................................................................................130

5.4.9 Deleting a HyperMetro Consistency Group............................................................................................................ 131

5.5 Importing Certificates.................................................................................................................................................132

6 FAQs.............................................................................................................................................135

6.1 What Can I Do If a Quorum Link Fails to Be Added Because the HyperMetro Arbitration Certificate Becomes

Invalid or the System Time Becomes Abnormal?............................................................................................................136

6.2 Active and Standby IP Ports Are Configured on the Quorum Server. After the Port in Use Is Down, the Quorum

Server Goes Offline. Why?...............................................................................................................................................137

6.3 How Do I Power Off Active-Active Storage Systems and Resume the HyperMetro Service?................................. 138

6.4 When Both the HyperMetro and Remote Backup Services Are Created, the Excessively Low Link Bandwidth

Between Storage Systems Causes the Remote Backup Service to Fail............................................................................139

6.5 How Can I Query HyperMetro LUN Identifiers?.......................................................................................................140

6.6 What Can I Do If the Remote Connection Fails to Be Created with the TOE Interface Module.............................. 140

6.7 In the SQL Server database scenario, how can I adjust parameters to reduce the I/O latency and achieve the optimal

performance?.................................................................................................................................................................... 141

6.8 How Can I Use OVA Templates to Quickly Deploy Virtual Quorum Servers?......................................................... 141

7 Troubleshooting........................................................................................................................ 146

7.1 A Quorum Link Fails to Be Added After the Quorum Server Is Replaced................................................................146

A How to Obtain Help.................................................................................................................148

A.1 Preparations for Contacting Huawei..........................................................................................................................148

A.1.1 Collecting Troubleshooting Information................................................................................................................ 148

A.1.2 Making Debugging Preparations............................................................................................................................ 149

A.2 How to Use the Document.........................................................................................................................................149

A.3 How to Obtain Help from Website............................................................................................................................ 149

A.4 Ways to Contact Huawei............................................................................................................................................149

B Glossary...................................................................................................................................... 150

C Acronyms and Abbreviations................................................................................................ 151

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About This Chapter

HyperMetro provides you with disaster recovery functions and enables you to synchronize and replicate data between storage arrays, monitor service operating status, and perform failovers. You can switch over services and implement service load sharing while your storage array is running.

1 Feature Description

1.1 Overview

This section describes the background, definition, and benefits of HyperMetro.

1.2 License Requirements and Compatible Products

This section describes the availability of HyperMetro in terms of the license requirement and applicable version.

1.3 Working Principle

This section introduces the basic concepts, I/O processing mechanism, and arbitration mechanism of HyperMetro and describes how to use HyperMetro for service switchover and recovery.

1.4 Impact and Restrictions

This section describes the impact and restrictions of HyperMetro feature.

1.5 Application Scenarios

This section introduces the application scenarios of HyperMetro.

1.1 Overview

This section describes the background, definition, and benefits of HyperMetro.

Background

With the rapid development of the information technology (IT), storage systems are becoming ever important for critical services in a variety of industries. Service interruptions in storage systems may lead to severe economic loss, damaged brand images, or critical data loss, especially in the fields of communications, finance, medical care, e-commerce, logistics, and governments. Therefore, service continuity is critical to the construction of storage systems. Traditionally, one production center and one disaster recovery center are constructed, and the

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disaster recovery center is active only when the production center is down. This disaster recovery system is facing the following challenges:

l If the production center encounters power supply failures, fires, floods, or earthquakes,

you must switch services from the production center to the disaster recovery center. Services are interrupted for a long time and service continuity cannot be ensured.

l The disaster recovery center remains idle for most of the time, lowering resource

utilization.

Definition

HyperMetro enables storage systems in two different data centers to process services simultaneously, establishing a mutual backup relationship. If the storage system in one data center malfunctions, the storage system in the other data center automatically takes over services without data loss or service interruption.

Benefits

Table 1-1 lists the benefits of HyperMetro.

1 Feature Description

Table 1-1 Benefits of HyperMetro

Benefit

Robust reliability If the storage system in one data center

High compatibility By integrating SmartVirtualization, HyperMetro

Description

malfunctions, the storage system in the other data center automatically takes over services without data loss or service interruption.

enables full utilization of storage resources, minimizes upgrade costs, and is fully compatible with storage systems from most vendors, including EMC, IBM, HDS, HP, and SUN.

1.2 License Requirements and Compatible Products

This section describes the availability of HyperMetro in terms of the license requirement and applicable version.

License Requirement

HyperMetro is a value-added feature that requires a software license for use on both local and remote storage systems.

Applicable products

Product Series

OceanStor 2000 V3 series OceanStor 2600 V3 V300R006

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Product Model Version

OceanStor V3 Series HyperMetro Feature Guide for Block

Product Series Product Model Version

1 Feature Description

OceanStor 5000 V3 series OceanStor 5300 V3, 5500

OceanStor 6000 V3 series OceanStor 6800 V3 V300R006

OceanStor 18000 V3 series OceanStor 18500 V3 and

Applicable Software Versions

Software

OceanStor UltraPath

OceanStor QuorumServer

NOTE

Log in to http://support.huawei.com/enterprise/ and you can register for an account on the website. After you log in with the applied user name and password. Choose Support > Enterprise Storage and click the corresponding product model to access the product document page.

l Input Version Mapping in the search box and press Enter to obtain the product document.

l Enter the software name to obtain the software.

V300R006

V3, 5600 V3, and 5800 V3

V300R006

18800 V3

Version

When configuring HyperMetro services, use OceanStor UltraPath V100R008C50SPC500 or later.

When configuring HyperMetro services, use OceanStor QuorumServer V300R006 or later.

1.3 Working Principle

This section introduces the basic concepts, I/O processing mechanism, and arbitration mechanism of HyperMetro and describes how to use HyperMetro for service switchover and recovery.

1.3.1 Basic Concepts

This section describes basic concepts of HyperMetro, including local logical unit number (LUN), remote LUN, dual-write, data change log (DCL), HyperMetro pair, HyperMetro consistency group, synchronization, paused, force start, priority switchover and so on.

Local LUN and Remote LUN

Local LUNs are LUNs that belong to the local storage system. Remote LUNs are LUNs that belong to the remote storage system.

Dual-Write

Dual-write enables the synchronization of application host I/O requests with both local and remote LUNs.

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DCL

DCLs record changes in the data of storage systems.

HyperMetro Domain

A HyperMetro domain consists of the local and remote storage systems, and the quorum server. Application servers can access data across data centers using a HyperMetro domain.

HyperMetro Pair

A HyperMetro pair indicates an active-active relationship between a local and remote LUN. With HyperMetro configured, a local and remote LUN form a HyperMetro pair. You must create HyperMetro pairs in a HyperMetro domain. By viewing the state of a HyperMetro pair, you can determine whether you need to perform operation such as synchronization, suspension, and priority switchover. After performing an operation, you can view the state of the HyperMetro pair to determine whether the operation succeeded. Configure a HyperMetro domain before configuring HyperMetro pairs.

1 Feature Description

HyperMetro Consistency Group

A HyperMetro consistency group is a collection of HyperMetro pairs that have a service relationship with each other. For example, the local storage system has three local LUNs that respectively store service data, logs, and change tracking information of a database. If data on any of the three LUNs becomes invalid, all data on the three LUNs becomes unusable. Upon configuration, create a consistency group and add the three HyperMetro pairs to the consistency group.

Synchronization

Synchronization refers to the synchronization of differential data between a local LUN and a remote LUN. Data synchronization takes place between two LUNs in a HyperMetro pair. You can synchronize data in multiple HyperMetro pairs in a consistency group.

Pause

Pause is a state indicating the suspension of a HyperMetro pair.

Force Start

To ensure data consistency when the local and remote storage systems malfunction simultaneously, HyperMetro stops hosts from accessing both. To quickly restore services, you can forcibly start the local or remote storage system.

Priority Switchover

Priority switchover indicates that the preferred site takes precedence during arbitration. If the HyperMetro replication network is down, the storage system that wins arbitration continues providing services to hosts. After the creation of a HyperMetro pair, the local data center is by default the preferred site and the remote data center is the non-preferred site.

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Locking Mechanism

To prevent different host I/Os from being written to the same location in the storage system at the same time, the storage system uses the locking mechanism to prevent access conflicts. The host I/O can only be written to the storage system that obtains the locking mechanism.

1.3.2 HyperMetro Solution Overview

This section describes the HyperMetro solution network and provides a logical HyperMetro network topology to show the mapping relationship and data flows between host applications and storage arrays.

HyperMetro enables active-active block storage services. LUN data is synchronized between two data centers in real time and can be accessed by hosts.

If the storage array in one data center malfunctions, host services are switched to the storage array in the other data center. If the link between two storage arrays in two data centers is down, only one storage array can be accessed by hosts. The quorum server determines which storage array continues providing services.

Figure 1-1 shows the HyperMetro solution network topology.

1 Feature Description

Figure 1-1 HyperMetro solution network topology

Data center A Data center B

Host cluster

Switch

FC/IP

Switch

Storage array A

Switch

Storage array B

Switch Switch

LAN/WAN

Quorum server

Quorum site

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Network of hosts and storage arrays

Same-city network

between data centers HyperMetro replication network

Quorum network

OceanStor V3 Series HyperMetro Feature Guide for Block

Network Overview

To ensure reliability of storage arrays, establish redundant links among the network between hosts and storage arrays, HyperMetro replication network, same-city network between data centers, and quorum network.

Table 1-2 Network Overview

1 Feature Description

Network

Network of hosts and storage systems

All hosts in the two data centers can form a cluster and host networks can interconnect across data centers.

Description

Network type

Networking mode

Supports 8 Gbit/s Fibre Channel, 16 Gbit/s Fibre Channel, 10GE, and GE networks.

l A fully interconnected network in which

each host is physically and logically connected to the storage arrays in both data centers.

l A host must connect to both storage arrays

using the same type of network.

l Dual-switch networking must be used. l The HyperMetro replication network,

storage-to-host network, and quorum network need to be physically isolated and common ports are not recommended.

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Network Description

1 Feature Description

HyperMetro replication network

This is the heartbeat network between the storage systems in the two data centers. It enables the storage systems to provide services for hosts concurrently and ensures data synchronization between them.

NOTE

The storage system sets link priorities for different types of information for transferring data. The link priority of heartbeat information is higher than that of data synchronization information.

Network type

l Supports 10GE, 8 Gbit/s Fibre Channel, and

16 Gbit/s Fibre Channel networks.

NOTE

When using the 10GE network, you are advised to use the L2 network.

l Network quality and bandwidth

requirements for deploying the network: – Bandwidth: ≥ peak service bandwidth

(total bandwidth of the two ends)

– Latency: The maximum supported RTT

is 10 ms (distance < 300 km)

NOTE

In practice, the latency is determined by the requirements of the application layer. The active/active solution must meet the minimum latency requirement. The round-trip time (RTT) of the Oracle RAC, SQL Server, and DB2 applications is less than 1 ms (with a distance of less than 100 km). The RTT of the VMware vSphere applications is less than 10 ms (with a distance of less than 300 km).

– No jitter and packet loss

– BER: ≤ 10

-12

l The HyperMetro replication network,

storage-to-host network, and quorum network need to be physically isolated and common ports are not recommended.

Same-city network between data centers

The storage systems in data centers A and B provide the same services for hosts. There is a mutual backup relationship between the two storage systems. If the storage system in one data center malfunctions, the storage system in the other data center automatically takes over services without data

Networking mode

Network type

Each controller on every storage array in both data centers has at least two redundant links. It is recommended that you use four redundant links.

The network uses bare fibers.

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Network Description

1 Feature Description

loss or service interruption.

Networking mode

l For Fibre Channel networks:

– The two data centers can be directly

connected using bare fibers if their distance is within 25 km. Ensure that the storage and application layers each have at least two pairs (four wires) of bare fibers for heartbeat interconnection in the cluster.

– If the data centers are greater than or

equal to 25 km apart, use dense wavelength division multiplexing (DWDM) devices to build the interconnection network between DCs.

l For IP networks:

– The two data centers can be directly

connected using bare fibers if their distance is within 80 km. If core switches are deployed, ensure that at least two pairs (four wires) of bare fibers are connected to the core switches for HyperMetro mirroring at the storage layer and heartbeat interconnection at the application layer.

– If the data centers are greater than or

equal to 80 km apart, use DWDM devices to interconnect them.

Quorum network If communication

between the storage systems in data centers A and B is interrupted or a storage system malfunctions, the quorum server determines which storage system is accessible.

Network type

l Quorum links support GE and 10GE

networks, but not a Fibre Channel network.

l Quorum links support IPv4 and IPv6

addresses.

l For versions earlier than V300R006C10, the

arbitration link port cannot use a storage device's management or maintenance network port. For V300R006C10 and later versions, the arbitration link port can use a storage device's management network port, but cannot use its maintenance network port.

l Network quality and bandwidth

requirements for deploying the network:

– Latency: RTT ≤ 50 ms – Bandwidth: ≥ 10 Mbit/s

l The HyperMetro replication network,

storage-to-host network, and quorum network need to be physically isolated and common ports are not recommended.

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Network Description

1 Feature Description

NOTE

A quorum server is deployed on the quorum network. If storage arrays in the two data centers encounter a device fault or a link between the storage arrays is down, the quorum server determines the access status of data center A and data center B according to the arbitration result.

Networking mode

l Quorum servers are supported but quorum

disks are not.

l You are advised to deploy the quorum server

at a third-place site. If there is no third-place site, you are advised to deploy the quorum server at the preferred site. In this case, the quorum server and related devices should have uninterruptible power supply (UPS) protection.

l A dual-switch network is recommended. A

GE/10GE port on each controller of a storage array is connected to the third-place quorum server and the service network ports on the quorum server are connected to two storage arrays, ensuring that the quorum server is connected to all controllers of each storage array.

l If each controller has two quorum ports,

connect the first quorum port on each controller to switch 1 and configure IP network segment 1. In addition, connect the second quorum port on each controller to switch 2 and configure IP network segment

l The quorum server can be a physical or a

virtual server. If a virtual server is used, you are advised to deploy VMware vSphere/ FusionSphere FT or HA to achieve high availability.

l Huawei Enterprise Cloud (HEC) can be used

as a quorum server. When the HEC is used as the quorum server, apply for a VM (including the CPU, memory, disk, and OS). The VM specifications are the same as those of the quorum server. Apply for 2 Mbit/s exclusive bandwidth and one elastic IP address for each disk array.

1.3.3 Arbitration Mechanism

If the link between the two data centers breaks down, they can no longer be synchronized and only one will continue providing services. HyperMetro supports two arbitration modes to determine which data center continues providing services and ensure data consistency:

l Static priority mode is used when there is no quorum server available. l Quorum server mode is used when quorum servers have been deployed.

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NOTE

The quorum server mode is recommended. After a quorum server is deployed, the non-preferred site of HyperMetro will automatically take over services once the preferred site becomes faulty, without causing HyperMetro service interruption.

Static Priority Mode

The static priority mode applies to scenarios where no third-place quorum server is deployed. In a HyperMetro pair, you can set one data center as the preferred site and the other as the non-preferred site.

l If the link between the two storage arrays in the two data centers is disconnected or the

storage array at the non-preferred site breaks down, the storage array at the preferred site continues providing services for hosts and the storage array at the non-preferred site stops.

l If the storage array at the preferred site breaks down, the storage array at the non-

preferred site cannot automatically take over HyperMetro services from the storage array at the preferred site. As a result, HyperMetro services stop. In this case, you must forcibly start the storage array at the non-preferred site to provide services for hosts.

NOTE

When you use OceanStor DeviceManager or CLI to power off a storage device, it will notify its peer storage device of taking over its services. This event is not a device fault.

1 Feature Description

In the following example, data center A is used as a preferred site. Table 1-3 describes the arbitration mechanism in static priority mode.

NOTE

You can set the Recovery Policy for HyperMetro pair failures by Modifying HyperMetro Pair Properties.

l Automatic: The system automatically synchronizes data for data recovery. l Manual: You must manually synchronize data for data recovery.

Table 1-3 Arbitration mechanism in static priority mode

Fault Example Fault Type HyperM

etro Pair

Arbitration Result

Running Status

Data center A Data center B

HyperMetro Pair

LUN LUN

The link between two storage arrays

To be synchroni zed

A continues providing services while B stops.

breaks down.

Data center A Data center B

HyperMetro Pair

LUN LUN

The storage array in data center B (non-

To be synchroni zed

A continues providing services

while B stops. preferred site) malfunctions.

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OceanStor V3 Series HyperMetro Feature Guide for Block

1 Feature Description

No.Fault Example Fault Type HyperM

Data center A Data center B

Black cable: HyperMetro replication network

Quorum Server Mode

In quorum server mode, the heartbeat network determines whether the storage arrays are working properly. If a malfunction occurs, each data center sends an arbitration request to the quorum server, and only the winner continues providing services.

The quorum site supports two quorum servers for V300R006C10 and later versions. The two quorum servers work in active/standby mode. Once the active quorum server is faulty, the system automatically switches to the standby quorum server to execute the arbitration function.

HyperMetro Pair

LUN LUN

The storage array in data center A (preferred site) malfunctions.

etro Pair Running Status

To be synchroni zed

Arbitration Result

Both A and B stop.

You must forcibly

start B to resume

providing services

for hosts.

In a HyperMetro pair, you can set one data center as the preferred site, which takes precedence in arbitration, and the other as the non-preferred site. In the following example, data center A is used as a preferred site. Table 1-4 and Table 1-5 describe the arbitration mechanisms when one and two quorum servers are deployed, respectively.

NOTE

You can set the Recovery Policy for HyperMetro pair failures by Modifying HyperMetro Pair Properties.

l Automatic: The system automatically synchronizes data for data recovery. l Manual: You must manually synchronize data for data recovery.

Table 1-4 Arbitration mechanism in single-quorum-server mode

Fault Example Fault Type HyperM

etro Pair

Arbitration Result

Running Status

Data center A Data center B

Quorum server

HyperMetro Pair

LUNLUN

The quorum server breaks down.

Normal Both A and B

continue providing services.

NOTE

HyperMetro automatically switches to static priority arbitration.

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1 Feature Description

No.Fault Example Fault Type HyperM

etro Pair Running Status

Quorum server

The link

Normal Both A and B

between one

HyperMetro Pair

Data center A Data center B

Quorum server

HyperMetro Pair

Quorum server

HyperMetro Pair

LUNLUN

storage array and the quorum server breaks down.

One storage array malfunctions.

The link between two storage arrays breaks down.

To be synchroni zed

Arbitration Result

continue providing services.

B continues providing services while A stops.

Result 1: A continues providing services while B stops.

Result 2: B continues providing services while A stops.

NOTE

l A has arbitration

priority, so the normal result is Result 1.

l (For

V300R006C10 and later versions) If the link between data center A and the application server has become faulty before the link between the two storage arrays breaks down, data center B will win the arbitration.

Quorum server

One storage array and the

HyperMetro Pair

LUNLUN

Data center A Data center B

quorum server both malfunction.

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To be synchroni zed

Both A and B stop.

NOTE

You must forcibly start B to resume providing services for hosts.

OceanStor V3 Series HyperMetro Feature Guide for Block

1 Feature Description

No.Fault Example Fault Type HyperM

etro Pair Running Status

Data center A Data center B

Quorum server

HyperMetro Pair

LUNLUN

The link between the two storage arrays and the link between one storage

To be synchroni zed

array and the quorum server both break down.

Data center A Data center B

Quorum server

HyperMetro Pair

LUNLUN

One storage array malfunctions and the link between the other storage

To be synchroni zed

array and the quorum server is down.

Arbitration Result

B continues providing services while A stops.

Both A and B stop.

NOTE

You must forcibly start B to resume providing services for hosts.

Data center A Data center B

Quorum server

HyperMetro Pair

Quorum server

HyperMetro Pair

The quorum server malfunctions

LUNLUN

and then the link between two storage arrays is down.

To be synchroni zed

Result 1: If the link is interrupted more than 60 seconds after the quorum server fails, A continues providing services while B stops.

Result 2: If the link is interrupted within 60 seconds of the quorum server failure, both A and B stop. You must forcibly start either A or B to resume providing services for hosts.

The quorum server malfunctions

LUNLUN

and the link between the quorum server and one storage array

Normal Both A and B

continue providing services.

NOTE

HyperMetro automatically switches to static priority arbitration.

is down.

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1 Feature Description

No.Fault Example Fault Type HyperM

etro Pair Running Status

Black cable: HyperMetro replication network Green cable: quorum network

Table 1-5 Arbitration mechanism in dual-quorum-server mode

Fault Example Fault Type HyperM

N o.

etro Pair Running Status

Quorum server

(active)

Quorum server

(standby)

The active quorum server

Normal The standby quorum

breaks down.

HyperMetro

Pair

LUNLUN

Data center A Data center B

Arbitration Result

server takes over the arbitration services from the active quorum server.

Both A and B continue providing services.

Quorum server

(active)

HyperMetro

Pair

Data center A Data cente B

Quorum server

(active)

HyperMetro

Pair

Data center A

Quorum server

(standby)

LUNLUN

Quorum server

(standby)

LUNLUN

Data cente B

The link between one storage array and the active quorum server breaks down.

One storage array malfunctions.

Normal The active quorum

server runs properly. Both A and B

continue providing services.

To be synchroni zed

The active quorum server runs properly.

B continues providing services while A stops.

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OceanStor V3 Series HyperMetro Feature Guide for Block

1 Feature Description

No.Fault Example Fault Type HyperM

etro Pair Running Status

Quorum server

(active)

Data center A Data cente B

Quorum server

(active)

Data center A Data cente B

HyperMetro

Pair

HyperMetro

Pair

Quorum server

(standby)

LUNLUN

Quorum server

(standby)

LUNLUN

The link between two storage arrays breaks down.

The active quorum server fails and then the storage array at the preferred site

To be synchroni zed

fails after more than 60 seconds.

Arbitration Result

The active quorum server runs properly.

Result 1: A continues providing services while B stops.

Result 2: B continues providing services while A stops.

NOTE

A has arbitration priority, so the normal result is Result 1.

The standby quorum server takes over the arbitration services from the active quorum server.

B continues providing services while A stops.

Quorum server

(active)

HyperMetro

Data center A Data cente B

Quorum server

Pair

(standby)

The link between the two storage arrays and the

LUNLUN

link between

To be synchroni zed

The active quorum server runs properly.

B continues providing services while A stops.

one storage array and the active quorum server both break down.

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OceanStor V3 Series HyperMetro Feature Guide for Block

1 Feature Description

No.Fault Example Fault Type HyperM

etro Pair Running Status

Quorum server

(active)

Data center A Data cente B

HyperMetro

Pair

Quorum server

(standby)

LUNLUN

The link between the active quorum server and non-preferred site breaks

To be synchroni zed

down and then the storage array at the preferred site fails after more than 60 seconds.

Quorum server

(active)

Data center A

HyperMetro

Pair

Quorum server

(standby)

LUNLUN

Data cente B

The active quorum server malfunctions and then the link between two storage

To be synchroni zed

arrays is down.

Arbitration Result

The standby quorum server takes over the arbitration services from the active quorum server.

B continues providing services while A stops.

The standby quorum server takes over the arbitration services from the active quorum server.

Result 1: If the link is interrupted more than 60 seconds after the active quorum server fails, A continues providing services while B stops.

If the link is interrupted within 60 seconds of the quorum server failure, both A and B may win the arbitration and continue providing services.

NOTE

A has arbitration priority, so generally A continues providing services while B stops.

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OceanStor V3 Series HyperMetro Feature Guide for Block

1 Feature Description

No.Fault Example Fault Type HyperM

Quorum server

(active)

Quorum server

(standby)

The active quorum server malfunctions

HyperMetro

Pair

LUNLUN

Data center A Data cente B

and the link between the active quorum server and one storage array is down.

Black cable: HyperMetro replication network Green solid cable: quorum network between the active quorum server and data centers Green dotted cable: quorum network between the standby quorum server and data centers

1.3.4 HyperMetro I/O Processing Mechanism

HyperMetro uses the dual-write and DCL technologies to synchronize data changes between two data centers, ensuring data consistency. In addition, HyperMetro enables the storage arrays in the two data centers to concurrently provide services for hosts.

Arbitration Result etro Pair Running Status

Normal The standby quorum

server takes over the

arbitration services

from the active

quorum server.

Both A and B

continue providing

services.

Basic Concepts

You are advised to read about the key concepts of HyperMetro before reading about the I/O processing mechanism. For details, see 1.3.1 Basic Concepts.

Write I/O Process

l Dual-write and DCL technologies have two ways of synchronizing data while services

l Two storage systems with HyperMetro installed can process I/O requests concurrently.

Figure 1-2 shows the write I/O process of an application host delivering an I/O request and

causing data changes.

are running. Dual-write enables the delivery of I/O requests from application servers to both local and remote caches, ensuring data consistency between caches. If the storage system in one data center malfunctions, the DCL records data changes in a data center. After the storage system recovers, the data changes are synchronized to the storage system, ensuring data consistency across data centers.

The locking mechanism prevents access conflicts that occur when different hosts access the same storage system at the same time. Data can be written to a storage system only after the locking mechanism grants permission to the storage system. If the locking mechanism does not grant priority, the storage system must wait until the previous I/O is complete. It must then obtain write permission after the locking mechanism releases the previous storage system.

NOTE

In the following figure, the write I/O accesses the local storage system, and the local storage system writes data to the remote storage system for dual-write purposes.

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Figure 1-2 Write I/O process

Host

1 Feature Description

Storage

DCL

LOG

Local storage array

HyperMetro management module

Local

cache

Local

LUN

DWDM

Same-city network

between data centers

Remote

cache

Remote

LUN

Remote storage array

1. An application host delivers a write I/O to the HyperMetro management module.

2. A log is recorded.

3. HyperMetro writes the write I/O to both the local and remote caches concurrently.

4. The local and remote caches return the write I/O result to HyperMetro.

5. A storage system returns the write I/O result to the application host after receiving

6. The storage system determines whether dual-write is successful.

Read I/O Process

Data on the LUNs of both storage systems is synchronized in real time and both are accessible to hosts. If the storage system in one data center malfunctions, the storage system in the other data center continues providing host services alone.

feedback from the local and remote caches.

– If the write I/O request is processed successfully, the log is deleted.

– If the write I/O fails to be written to the local or remote cache, the log is converted

into a DCL. The DCL records the differential data between the local and remote LUNs.

NOTE

If the write I/O fails to be written to the local or remote cache, HyperMetro services are suspended and the storage system in each data center sends an arbitration request to the quorum server. The storage system that wins the arbitration continues providing services and the one that fails stops. In the background, the storage system uses the DCL to synchronize data. Once the data on the local LUN is identical to the data on the remote LUN, HyperMetro services are restored.

The DCL is stored on all the disks in the disk domain and four-disk RAID 1 is used for data protection while storage system logs are stored on coffer disks.

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NOTE

l UltraPath is recommended for HyperMetro. Huawei UltraPath to meet HyperMetro requirements.

After the optimization, UltraPath can identify host locations so that hosts can access the nearest storage array, reducing cross-site accesses and latency while improving access efficiency and storage performance.

l If the customer needs to use non-Huawei multipathing software on the application server, the

function of Uses third-party multipath software for initiators must be enabled on Huawei storage. After this function is enabled, third-party multipathing software can identify and aggregate LUNs for servers to access to ensure normal operation of server services.

Figure 1-3 shows the read I/O process.

Figure 1-3 Read I/O process

HyperMetro management

Application

host

module

1 Feature Description

Local

LUN

Data center A

Remote

LUN

Data center B

1. An application host applies for read permission from the HyperMetro management module.

NOTE

If the link between the storage arrays in the two data centers is down, the quorum server determines which storage array continues providing services for hosts.

2. The HyperMetro management module enables the local storage system to respond to the read I/O request made by the host.

3. If the local storage system is operating properly, it returns data to the HyperMetro management module. If not, the HyperMetro management module enables the host to read data from the remote storage system.

4. If the local storage array is working improperly, the HyperMetro management module enables the host to read data from the remote storage array. The remote storage array returns data to the HyperMetro management module.

5. The read I/O request made by the host is processed successfully.

1.3.5 Functions of a HyperMetro Consistency Group

A consistency group is a collection of multiple HyperMetro pairs. It ensures that the read/ write control policies of the multiple LUNs on a storage array are synchronized.

In medium- and large-sized database applications, data, logs, and modification information are stored on different LUNs. If data on one of the LUNs becomes unavailable, data on the other LUNs also becomes invalid. A consistency group is a collection of multiple HyperMetro

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pairs. It ensures that the read/write control policies of the multiple LUNs on a storage array are synchronized. The operation and control policies of all members that have been added to a consistency group must be consistent with those of the consistency group.

HyperMetro applications can use a consistency group to manage multiple HyperMetro pairs in a unified manner.

The following compares synchronization in a consistency group with synchronization without using a consistency group to prove that a consistency group is effective in preventing data loss.

Without a HyperMetro Consistency Group

If LUNs are not added to a HyperMetro consistency group, the possibility of data loss is quite high for these LUNs, as shown in Figure 1-4.

1 Feature Description

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OceanStor V3 Series HyperMetro Feature Guide for Block

Figure 1-4 Without a HyperMetro consistency group

1 Feature Description

Local storage array

Local

LUN01

Local

LUN02

Local

LUN03

Local

LUN01

Local

LUN02

Local

LUN03

Before data changes

HyperMetro pair 01

HyperMetro pair 02

HyperMetro pair 03

After data changes

HyperMetro pair 01

HyperMetro pair 02

HyperMetro pair 03

Remote storage array

Remote

LUN01

Remote

LUN02

Remote

LUN03

Remote

LUN01

Remote

LUN02

Remote

LUN03

1. No consistency group is created.

· Data, logs, and modification information of a database application are stored on local LUN01, LUN02, and LUN03 respectively.

· No consistency group is created on the local storage array.

2. Synchronization fails, resulting in data inconsistency.

Data synchronization fails between two LUNs in HyperMetro pair 02 due to a fault of the HyperMetro pair. Data synchronization succeeds between LUNs in HyperMetro pairs 01 and 03.

Phases in a process of data becoming invalid

Data recovery

Local

HyperMetro pair 01

LUN01

Local

HyperMetro pair 02

LUN02

Local

HyperMetro pair 03

LUN03

With a HyperMetro Consistency Group

If LUNs are added to a HyperMetro consistency group, no data is lost, as shown in Figure

1-5.

Remote

LUN01

Remote

LUN02

Remote

LUN03

3. Data becomes invalid.

After the local storage array malfunctions due to a disaster, data on the remote storage array is used for data recovery. Data in the database of the local storage array is still invalid because data on the three local LUNs are not stored at the same point in time.

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Figure 1-5 With a HyperMetro consistency group

1 Feature Description

Local storage array

Local

LUN01

Local

LUN02

Local

LUN03

Local

LUN01

Local

LUN02

Local

LUN03

Before data changes

HyperMetro pair 01

HyperMetro pair 02

HyperMetro pair 03

Consistency group 01

After data changes

HyperMetro pair 01

HyperMetro pair 02

HyperMetro pair 03

Consistency group 01

Remote storage array

Remote

LUN01

Remote

LUN02

Remote

LUN03

Remote

LUN01

Remote

LUN02

Remote

LUN03

1. A consistency group is created.

· Data, logs, and modification information of a database application are stored on local LUN01, LUN02, and LUN03 respectively.

· Consistency group 01 is created on the local storage array and three HyperMetro pairs are added to the consistency group.

2. The consistency group stops the replication task.

· HyperMetro pair 02 encounters a fault during data synchronization.

· The consistency group stops HyperMetro pairs 01 and 03 immediately.

· After the fault is rectified, data is replicated.

Data recovery

Phases in a process of ensuring data validity by a consistency group

Local

HyperMetro pair 01

LUN01

Local

HyperMetro pair 02

LUN02

Local

HyperMetro pair 03

LUN03

Consistency group 01

1.4 Impact and Restrictions

This section describes the impact and restrictions of HyperMetro feature.

Network Restrictions

For details about network restrictions, see HyperMetro Solution Overview.

Remote

LUN01

Remote

LUN02

Remote

LUN03

3. The consistency group ensures data validity.

After a disaster occurs, the data on the remote storage array is used for data recovery. The data in the database is valid.

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+ 130 hidden pages

Huawei OceanStor 2000 V3, OceanStor 5500 V3, OceanStor 6000 V3, OceanStor 5600 V3, OceanStor 6800 V3 Features Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

About This Document

Contents

1 Feature Description

1.1 Overview

1.2 License Requirements and Compatible Products

1.3 Working Principle

1.3.1 Basic Concepts

1.3.2 HyperMetro Solution Overview

1.3.3 Arbitration Mechanism

1.3.4 HyperMetro I/O Processing Mechanism

1.3.5 Functions of a HyperMetro Consistency Group

1.4 Impact and Restrictions