Xsan
Administrator’s Guide for Xsan 1.4
K Apple Computer, Inc.
© 2006 Apple Computer, Inc. All rights reserved.
Under the copyright laws, this manual may not be copied, in whole or in part, without the written consent of Apple.
The Apple logo is a trademark of Apple Computer, Inc., registered in the U.S. and other countries. Use of the “keyboard” Apple logo (Option-Shift-K) for commercial purposes without the prior written consent of Apple may constitute trademark infringement and unfair competition in violation of federal and state laws.
Every effort has been made to ensure that the information in this manual is accurate. Apple is not responsible for printing or clerical errors.
Apple
1 Infinite Loop
Cupertino, CA 95014-2084 408-996-1010 www.apple.com
Apple, the Apple logo, Final Cut Pro, Mac, Macintosh, the Mac logo, Mac OS, Panther, Xsan, and Xserve are trademarks of Apple Computer, Inc., registered in the U.S. and other countries.
Finder and Tiger are trademarks of Apple Computer, Inc.
ADIC and StorNext are registered trademarks of Advanced Digital Information Corporation.
Intel and Intel Core are trademarks of Intel Corp. in the U.S. and other countries.
PowerPC and the PowerPC logo are trademarks of International Business Machines Corporation, under license therefrom.
Other company and product names mentioned herein are trademarks of their respective companies. Mention of third-party products is for informational purposes only and constitutes neither an endorsement nor a recommendation. Apple assumes no responsibility with regard to the performance or use of these products.
The product described in this manual incorporates copyright protection technology that is protected by method claims of certain U.S. patents and other intellectual property rights owned by Macrovision Corporation and other rights owners. Use of this copyright protection technology must be authorized by Macrovision Corporation and is intended for home and other limited viewing uses only unless otherwise authorized by Macrovision Corporation. Reverse engineering or disassembly is prohibited.
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Simultaneously published in the United States and Canada.
034-3767-A/07-21-06
11About This Book
12What’s New in Xsan 1.4
12 Version Compatibility
14 Upgrading from an Earlier Version of Xsan
14For More Information
15Notation Conventions
17 Chapter 1: Overview of Xsan
17 What Is Xsan?
19 Xsan Storage Area Networks
21 Shared SAN Volumes
21Controllers and Clients
22SAN Connections
23How Xsan Storage Is Organized
24LUNs
25Storage Pools
26Volumes
28 Folders with Affinities
28 How Xsan Utilizes Available Storage
3
28Metadata and Journal Data
29Striping at a Higher Level
30Security
30Expanding Storage
31Xsan Capacities
33Chapter 2: Setting Up a Storage Area Network
33Hardware and Software Requirements
34Supported Computers
34Supported Storage Devices
35Fibre Channel Fabric
36Ethernet TCP/IP Network
37Directory Services
38Outgoing Mail Service
39Planning Your SAN
41 Planning Considerations and Guidelines
50Connecting Computers and Storage Devices
51Preparing LUNs
51Using the Xsan Admin Application
52Installing Just the Xsan Admin Application
52 Connecting Through a Firewall
52 Xsan Admin Preferences
52Getting Help
53Using the Command Line
4Contents
53SAN and Volume Setup Summary
54Setting Up an Xsan Volume on a Storage Area Network
74Renaming a SAN
75Removing a SAN
75 Setting Up Additional SANs
77Chapter 3: Managing SAN Storage
78Adding Storage
79Restoring the Previous Volume Configuration After Changes
79About Rearranging Fibre Channel Connections
80Adding LUNs to a Storage Pool
82 Adding a Storage Pool to a Volume
84 Adding a Volume to a SAN
86Assigning a Storage Pool Affinity to a Folder
87Assigning an Affinity to a Folder Within a Folder
89Removing an Affinity
90Changing Storage Pool Settings
91Renaming a Storage Pool
92Choosing the Types of Files Stored on a Storage Pool
92 Setting Storage Pool Stripe Breadth
94Setting the Selection Method for Multiple Connections
95Changing Volume Settings
96Renaming a Volume
97Setting the Block Allocation Size
Contents |
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99Setting the Volume Allocation Strategy
100Enabling or Disabling Access Control Lists
101Choosing the Windows ID Mapping Method
101Checking Volume Fragmentation
102Defragmenting a Volume
103Checking the Integrity of a Volume
104Repairing a Volume
105Chapter 4: Managing Clients and Users
106Adding a Client
107Adding a Client to a StorNext SAN
108Mounting a Volume on a Client
109Controlling Client and User Access
109Controlling Access to Folders on Volumes
110Setting Up Access Control Lists
110 Unmounting a Volume on a Client
110Restricting a Client to Read-Only Access
111Removing a Client from a SAN
111Removing Xsan Software from a Computer
112Mapping Windows User and Group IDs
114Setting User and Group Quotas
115About Xsan Quotas
117 Checking User Quota Use
119 Helping Clients Check Their Own Quotas
6Contents
120Creating Local Home Folders for Network Accounts
121Chapter 5: Managing Metadata Controllers
122Adding a Controller
123Setting Controller Failover Priority
124Switching to a Standby Controller
125Finding Out Which Controller Is Hosting a Volume
127Listing the Volumes Hosted by a Controller
128Changing a Controller’s IP Address
129Upgrading Controller Software
130Monitoring Controller Status
131Chapter 6: Monitoring SAN Status
132Locking Xsan Admin Views for Secure Monitoring
133Checking Overall SAN Status
134Checking Overall Volume Status
135Checking Free Space on a Volume
136Checking Free Space on a Storage Pool
136 Checking Quota Use
136Viewing a Controller’s CPU and Network Utilization
137Viewing File System CPU and Memory Utilization
138Setting Up Status Notifications
139Checking the Status of File System Processes
139 Viewing Xsan Logs
Contents |
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140Checking Volume Clients
141Checking for Fibre Channel Connection Failures
141 Checking the State of Xserve RAID Systems
143 Chapter 7: Solving SAN Problems
143 A Dialog on a Client Reports That a LUN Is Unreadable
143You’re Unable to Connect to a Computer Using Xsan Admin
144You’re Unable to Install the Xsan Software
144 Some Computers Aren’t Listed in Xsan Admin
144You’re Unable to Mount a Volume on a Client
145Xserve RAID LUNs Aren’t Accessible over Fibre Channel
145You’re Unable to Restart a Volume After Adding LUNs or Storage Pools
146Some LUNs Aren’t Listed in Xsan Admin
147Some LUNs Are Listed Twice in Xsan Admin
147Files and Folders Created by Mac OS 9 Computers Show the Wrong Creation Date
148Problems Using Command-Line Tools
148A LUN Doesn’t Have as Much Space as Expected
149You’re Unable to Rename an Xsan Volume in the Finder
149 |
Fibre Channel Performance Is Poorer Than Expected |
149 |
A Client User Sees Error Code –1425 |
149 |
File Copy Doesn’t Finish |
150 |
A Client is Unable to Use a Volume After a Fibre Channel Interruption |
150 |
SAN Performance Declines Periodically and Predictably |
151 |
You’re Unable to Add a Storage Pool |
8Contents
152You’re Unable to Add LUNs to a Storage Pool
153The Capacity of a Larger LUN is Listed as 2 Terabytes
155Appendix A: Combining Xsan and StorNext Clients and Controllers
155Terminology
156Compatible Software Versions
156Licensing
157Adding Macintosh Clients to a StorNext SAN
159 Using Xsan Controllers with StorNext Clients
161Appendix B: Using the Command Line
161Using the Shell Commands
162Sending Commands to Remote Computers
162Viewing the Man Pages
163Notation Conventions
164The Commands
164 Viewing or Changing Volume and Storage Pool Settings (cvadmin)
168 Copying Files or Folders (cvcp)
171Checking or Repairing a Volume (cvfsck)
172Labeling, Listing, and Unlabeling LUNs (cvlabel)
173Creating a Folder with an Affinity (cvmkdir)
174Creating and Preallocating a File (cvmkfile)
175Initializing a Volume (cvmkfs)
176Applying Volume Configuration Changes (cvupdatefs)
Contents |
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176Starting a Volume Controller (fsm)
177Starting a Port Mapper Process (fsmpm)
177 Defragmenting a File, Folder, or Volume (snfsdefrag)
179Mounting an Xsan Volume
180Unmounting an Xsan Volume
181Viewing Logs
181 The Configuration Files
181 Examples
183 Glossary
187 Index
10 Contents
Preface
Use this guide to learn how to set up and manage Xsan volumes on a storage area network.
This guide shows how to use Xsan to combine Xserve RAID arrays and slices into large, easy-to-expand volumes of storage that clients use like local disks but are actually shared over a high-speed Fibre Channel fabric.
Chapter 1 provides an overview of Xsan and how you can use it to organize RAID arrays into shared volumes of storage.
Chapter 2 includes hardware and software requirements, SAN planning guidelines, and basic steps for setting up an Xsan volume.
Chapter 3 contains instructions for expanding storage, creating folders with affinities, changing volume and storage pool settings, and checking, defragmenting, and repairing SAN volumes.
Chapter 4 shows how to add client computers to a SAN, mount volumes on clients, control client and user access to SAN files, and control user space using quotas.
Chapter 5 contains information about managing volume metadata controllers.
Chapter 6 includes instructions for monitoring and automatically reporting the condition of a SAN.
11
Chapter 7 lists solutions to common problems you might encounter.
Appendix A contains information to help you combine Xsan controllers or clients with ADIC StorNext controllers or clients on the same SAN.
Appendix B describes command-line utilities and configuration files you can use to manage an Xsan SAN using Terminal.
Xsan 1.4 offers these new features and capabilities:
ÂYou can use access control lists (ACLs) to manage user access to Xsan volumes.
ÂXsan runs on Intel-based Macintosh computers.
The following table shows which versions of Xsan and StorNext controllers and clients can be used on the same SAN.
Important: If you set up a LUN that is larger than 2 terabytes (TB), be aware that older clients (those running Xsan on Mac OS X 10.3 Panther or Xsan 1.2 or earlier on
Mac OS X 10.4 Tiger) cannot read these large LUNs. A dialog appears on these older clients that says the LUN is unreadable. Be sure to click Ignore to dismiss this dialog. Do not click Format, or information on the corresponding Xsan volume will be lost. If you use LUNs greater than 2 TB, you should upgrade all SAN clients to Xsan 1.3 or later on Mac OS X or Mac OS X Server v10.4.
12 Preface About This Book
Controller |
Client |
Compatible |
Xsan 1.4 |
Xsan 1.4 |
Yes |
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Xsan 1.3 (Mac OS X v10.4) |
Yes |
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Xsan 1.3 (Mac OS X v10.3) |
Yes, for LUNs < 2 TB |
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Xsan 1.2 or earlier |
No |
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StorNext 2.8 |
No |
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StorNext FX 1.3 or 1.4 |
Yes |
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StorNext 2.6 or 2.7 |
Yes |
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StorNext 2.5 or earlier |
No |
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Xsan 1.3 (Mac OS X v10.4) |
Xsan 1.4 |
No |
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Xsan 1.3 (Mac OS X v10.4) |
Yes |
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Xsan 1.3 (Mac OS X v10.3) |
Yes |
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StorNext FX 1.3 or 1.4 |
Yes |
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StorNext 2.6 or 2.7 |
Yes |
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StorNext 2.5 or earlier |
No |
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StorNext 2.8 |
Xsan 1.4 or 1.3 |
Yes |
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StorNext 2.7 |
Xsan 1.4 or 1.3 |
Yes |
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StorNext 2.6 or earlier |
Xsan 1.4 or 1.3 |
No |
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Preface About This Book |
13 |
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For more information about migrating your SAN storage to Xsan 1.4 from an earlier version of Xsan, including tips for upgrading with the least impact on existing storage, see the Xsan Migration Guide at www.apple.com/server/documentation/.
For more information about Xsan, consult these resources:
Read Me documents—important updates and special information. Look for them on the Xsan installation disc.
Xsan website (www.apple.com/xsan/)—gateway to extensive product and technology information.
Xsan Support website (www.apple.com/support/xsan/)—access to articles about Xsan from Apple’s support organization.
Apple customer training (train.apple.com/)—instructor-led and self-paced courses for honing your Xsan administration skills.
Apple discussion groups (discussions.info.apple.com/)—a way to share questions, knowledge, and advice with other Xsan administrators.
Apple mailing list directory (www.lists.apple.com/)—subscribe to mailing lists so you can communicate with other Xsan administrators using email.
14 Preface About This Book
The following conventions are used in this book wherever shell commands or other command-line items are described.
Notation |
Indicates |
fixed-width font |
A command or other terminal text |
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$ |
A shell prompt |
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[text_in_brackets] |
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(one|other) |
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underlined |
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[...] |
A parameter that may be repeated |
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<angle_brackets> |
A displayed value that depends on your SAN configuration |
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Preface About This Book |
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1 |
Overview of Xsan |
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This chapter gives you an overview of Xsan and storage area networks.
Read this chapter for an overview of Xsan and how you can use it to set up a storage area network (SAN) to provide fast, shared storage.
Xsan is a storage area network file system and a management application (Xsan Admin) that you can use to provide users or applications on client computers with shared high-speed access to expandable storage.
17
Mac OS X
San Volume
Xsan lets you |
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Storage
pools
RAID arrays (LUNs)
18 Chapter 1 Overview of Xsan
A storage area network is a way of connecting computers to storage devices that gives users very fast access to files and gives administrators the ability to expand storage capacity as needed without interrupting users.
An Xsan SAN consists of:
ÂVolumes of shared storage, stored on Xserve RAID systems, available to clients as mounted volumes that they can use like local disks
ÂAt least one computer acting as a metadata controller that coordinates access to the shared volumes
ÂClient computers that access storage in accordance with established permissions and quotas
ÂUnderlying Fibre Channel and Ethernet networks
The following illustration shows the physical components of a typical Xsan SAN.
Chapter 1 Overview of Xsan |
19 |
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Ethernet - TCP/IP (Public) |
Ethernet - TCP/IP (Private) |
Metadata controller
Standby controller
Fibre
Channel switch
Xserve RAID storage
Intranet/
Internet
20 Chapter 1 Overview of Xsan
Users and applications see shared SAN storage as local volumes. Xsan volumes are logical disks made up of groups of RAID arrays. The elements you combine to create an Xsan volume are described under “How Xsan Storage Is Organized” on page 23.
When you add a computer to an Xsan SAN, you specify whether it will play the role of client, controller, or both.
Controllers
When you set up an Xsan SAN, you assign at least one computer to act as the controller. The controller manages the SAN volume metadata, maintains a file system journal, and controls concurrent access to files. Metadata includes such information as where files are actually stored and what portions of available storage are allocated to new files.
For high availability, you should add more than one controller to a SAN, as shown in the illustration on page 20. If the primary controller fails, the standby controller takes over. Though not recommended for best performance, controllers can also act as clients, so you can use a standby controller as a working client while the primary controller is operational.
Clients
The computers that users or applications use to access SAN volumes are called clients. Clients communicate with controllers over the Ethernet network but use Fibre Channel to send and retrieve file data to and from the RAID systems that provide storage for the volumes.
Chapter 1 Overview of Xsan |
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Xsan uses independent networks to connect storage devices, metadata controllers, and client computers: a Fibre Channel network and one or two Ethernet networks.
User Data Over Fibre Channel
User data is transferred over high-speed Fibre Channel connections. Controllers also use a Fibre Channel connection to move metadata to and from the volume.
Metadata Over Ethernet
To eliminate unnecessary traffic on the Fibre Channel connections, controllers and clients use an Ethernet network to exchange file system metadata. (When a controller reads or writes metadata on a volume, it uses Fibre Channel.) The Xsan Admin application also uses the Ethernet connection to let you manage the SAN.
To prevent Internet or intranet traffic from interfering with metadata communications, you should set up separate Ethernet networks as shown in the illustration on page 20.
Fibre Channel Multipathing
Xsan can take advantage of multiple Fibre Channel connections between clients and storage. Xsan can alternate between connections for each read and write, or assign each LUN in a volume to one of the connections when the volume is mounted.
22 Chapter 1 Overview of Xsan
Users use an Xsan volume the same way they use a local disk. What they don’t see is that the SAN volume actually consists of numerous physical disks combined on several levels using RAID techniques.
The following illustration shows an example of how disk space provided by the individual drive modules in several Xserve RAID systems is combined into a volume that users see as a large local disk.
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Storage pool |
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Storage pool |
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Chapter 1 Overview of Xsan |
23 |
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The following paragraphs describe these storage elements and how you organize them to create shared Xsan volumes.
The smallest storage element you work with in Xsan is a logical storage device called a LUN (a SCSI logical unit number). In most storage area networks a LUN represents a group of drives such as a RAID array or a JBOD (just a bunch of disks) device. In Xsan, LUNs are Xserve RAID arrays or slices.
You create a LUN when you use the RAID Admin application to create an Xserve RAID array. The controller hardware and software in the Xserve RAID system combine individual drive modules into an array based on the RAID scheme you choose. Each array appears on the network as a separate LUN. If you slice an array, each slice appears as a LUN.
One of your first tasks when you set up a SAN volume is to prepare LUNs. If the two RAID 5 arrays on a new Xserve RAID are not right for your application, you can use RAID Admin to create arrays based on other RAID schemes. For help choosing schemes for your LUNs, see “Choosing RAID Schemes for LUNs” on page 44.
The illustration on page 23 shows four Xserve RAID systems that each host two arrays. Half of the arrays use a RAID 0 scheme (striping only) for speed while the others use RAID 5 (distributed parity) to ensure against data loss. Xsan sees the arrays as LUNs that can be combined to create a volume.
After your Xserve RAID LUNs are set up, you label and initialize them for use with the Xsan file system using Xsan Admin.
24 Chapter 1 Overview of Xsan
LUNs are combined to form storage pools. A storage pool in a small volume might consist of a single RAID array, but storage pools in many volumes consist of multiple arrays.
Xsan distributes file data in parallel across the LUNs in a storage pool using a RAID 0 (striping) scheme. So, you can improve a client’s access speed by distributing available storage over several LUNs in a storage pool.
You can set up storage pools that have different performance or recoverability characteristics and assign folders to them using affinities. Users can then select where to store files based on their need for speed or safety. See “Folders with Affinities” on page 28.
The illustration on page 23 shows eight LUNs combined into two storage pools, one pool consisting of RAID 0 (fast, but not recoverable) arrays and the other made up of RAID 5 (not as fast, but recoverable) arrays. Xsan stripes data across the four LUNs in each storage pool.
You use Xsan Admin to add available LUNs to specific storage pools.
Chapter 1 Overview of Xsan |
25 |
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Storage pools are combined to create the volumes that users see. From the user’s perspective, the SAN volume looks and behaves just like a large local disk, except that:
ÂThe size of the volume can grow as you add underlying arrays or storage pools
ÂOther users on the SAN can access files on the volume at the same time
In the illustration on page 23, two storage pools are combined to create a single shared volume.
You create volumes and mount them on client computers using the Xsan Admin application.
26 Chapter 1 Overview of Xsan
The following screen image shows how LUNs, storage pools, and volumes appear as you organize them in Xsan Admin. This example shows a SAN named “Editing SAN” with a single shared volume named “SanVol.” Storage for the volume is provided by two storage pools,“Meta” and “Data,” the first based on a single LUN and the second on two. Each of the LUNs is a 3-disk RAID 5 array on an Xserve RAID using 115 GB drive modules.
SAN
Volume
LUN
Storage pool
Chapter 1 Overview of Xsan |
27 |
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To control which storage pool is used to store specific files (for example, to provide different levels of service for different users or applications), you can associate a folder on an Xsan volume with one of the storage pools that make up the volume.
If, for example, you set up storage pools with different balances of performance and data redundancy, users can choose between faster and safer storage by putting files in the appropriate folder.
In the illustration on page 23, a predefined folder has an affinity for the faster storage pool that is based on RAID 0 arrays. Any file that a user copies into this folder is automatically stored on the faster arrays. A second folder is associated with the more secure RAID 5 storage.
Xsan stores both user files and file system data on SAN volumes, and stripes data across the LUNs in a volume for better performance.
Xsan records information about the files in an Xsan volume using metadata files and file system journals. File system metadata includes information such as which specific parts of which disks are used to store a particular file and whether the file is being accessed. The journal data includes a record of file system transactions that can help ensure the integrity of files in the event of a failure.
28 Chapter 1 Overview of Xsan
These files are managed by the Xsan metadata controller, but are stored on SAN volumes, not on the controller itself. By default, metadata and journal data are stored on the first storage pool you add to a volume. You can use Xsan Admin to choose where these files are stored when you add storage pools to a new volume.
When you write a file to a RAID array using RAID 0 (striping), the file is broken into segments that are spread across the individual disk drives in the array. This improves performance by writing pieces of the file in parallel (instead of one piece at a time) to the individual disks in the array. Xsan applies this same technique at a second, higher level in the storage hierarchy. Within each storage pool in a volume, Xsan stripes file data across the individual LUNs that make up the storage pool. Once again, performance is improved because data is written in parallel.
You can tune SAN performance by adjusting the amount of data written to each LUN in a storage pool (the “stripe breadth”) to suit a critical application.
Chapter 1 Overview of Xsan |
29 |
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As the SAN administrator, you can control access to shared volumes in several ways.
First, users cannot browse or mount SAN volumes. Only a SAN administrator can specify which volumes are mounted on which client computers. One way you can control access to data is to mount a volume only on appropriate client computers.
To prevent users from modifying data on a volume, you can mount the volume with read-only access.
You can control user access to folders on a volume by setting up access control lists (ACLs) in Workgroup Manager or by specifying owner, group, and general access permissions in the Finder.
You can also set up zones in the underlying Fibre Channel network to segregate users and volumes.
There are two ways you can add free space to an Xsan volume:
ÂAdd Xserve RAID systems (new LUNs) to existing storage pools
ÂAdd entire new storage pools to volumes
Both methods require you to unmount and remount the volume on clients.
You can also add new volumes to a SAN at any time.
For information about expanding Xsan storage, see “Adding Storage” on page 78.
30 Chapter 1 Overview of Xsan