Gateway S466 User Manual
ADAC Ultra2 S466
Single Ended and Low-
Voltage Differential SCSI
PCI RAID Controller
Hardware Guide
8503624 A MAN US ADAC U2 S466 GDE R0
8/14/98
© Copyright 1998 Gateway, Inc.
All rights reserved.
This publication contains proprietary information which is protected by copyright. No part of
this publication can be reproduced, transcribed, stored in a retrieval system, translated into any
language or computer language, or transmitted in any form whatsoever without the prior written
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Revision History
6/8/98 Initial release.
ADAC Ultra2 S466 Hardware Guide
ii
Table of Contents
1 Overview...............................................................1
Single Ended and Differential SCSI Buses ..............................2
Maximum Cable Length for SCSI Standards ...........................2
Documentation.........................................................................3
ADAC Ultra2 S466 Block Diagram.........................................4
2 Introduction to RAID............................................5
RAID Benefits..........................................................................5
In This Chapter.........................................................................6
ADAC Ultra2 S466 – Host-Based RAID Solution...................7
RAID Overview.......................................................................8
Consistency Check...................................................................8
Fault Tolerance ........................................................................8
Disk Striping............................................................................9
Disk Spanning........................................................................10
Disk Mirroring .......................................................................11
Parity......................................................................................12
Hot Spares..............................................................................13
Disk Rebuild...........................................................................14
Logical Drive .........................................................................15
Hot Swap................................................................................15
SCSI Drive States...................................................................16
Logical Drive States...............................................................16
Disk Array Types...................................................................17
Enclosure Management..........................................................17
3 RAID Levels........................................................19
Selecting a RAID Level.........................................................20
RAID 0...................................................................................21
RAID 1...................................................................................22
RAID 3...................................................................................23
RAID 5...................................................................................25
RAID 10.................................................................................26
RAID 30.................................................................................27
RAID 50.................................................................................28
4 ADAC Ultra2 S466 Features ..............................29
Hardware Requirements.........................................................30
Configuration Features........................................................... 30
Hardware Architecture Features.............................................31
Array Performance Features...................................................31
RAID Management Features..................................................32
Fault Tolerance Features........................................................32
Contents
iii
Software Utilities....................................................................33
Operating System Software Drivers.......................................33
ADAC Ultra2 S466 Specifications.........................................34
PCI Bridge/CPU.....................................................................35
Cache Memory.......................................................................35
ADAC Ultra2 S466 BIOS ......................................................35
Onboard Speaker.................................................................... 36
Serial Port...............................................................................36
SCSI Bus................................................................................36
SCSI Connectors....................................................................37
SCSI Termination...................................................................37
SCSI Firmware.......................................................................37
RAID Management ................................................................38
Fault-Tolerance Features........................................................39
Compatibility..........................................................................40
Summary................................................................................40
5 Configuring ADAC Ultra2 S466.........................41
Configuring SCSI Physical Drives.........................................41
Current Configuration ............................................................42
Logical Drive Configuration ..................................................42
Physical Device Layout ..........................................................43
Configuring Arrays.................................................................45
Configuration Strategies.........................................................46
Assigning RAID Levels..........................................................48
Configuring Logical Drives....................................................48
Optimizing Data Storage........................................................49
Planning the Array Configuration..........................................50
Array Configuration Planner..................................................51
6 Hardware Installation.........................................53
Checklist.................................................................................53
Installation Steps....................................................................54
Step 1 Unpack........................................................................55
Step 2 Power Down................................................................55
Step 3 Configure Motherboard...............................................55
Step 4 Install Cache Memory.................................................56
Step 5 Set Jumpers.................................................................58
ADAC Ultra2 S466 Card Layout...........................................58
Step 6 Set Termination........................................................... 61
SCSI Termination...................................................................62
Step 7 Install ADAC Ultra2 S466..........................................65
Step 8 Connect SCSI Cables..................................................66
Step 9 Set Target IDs .............................................................67
Device Identification on ADAC Ultra2 S466.........................68
Step 10 Power Up ..................................................................69
ADAC Ultra2 S466 Hardware Guide
iv
Step 11 Run ADAC BIOS Setup............................................70
Step 12 Install Operating System Driver................................70
Summary................................................................................72
7 Troubleshooting.................................................73
BIOS Boot Error Messages ....................................................75
Other BIOS Error Messages...................................................77
DOS ASPI Driver Error Messages.........................................78
Other Potential Problems .......................................................79
A SCSI Cables and Connectors............................83
SCSI Connectors....................................................................83
68-Pin High Density SCSI Internal Connector.......................83
High-Density 68-Pin SCSI Connector Pinout........................89
68-Pin Connector Pinout for LVD SCSI................................91
B Audible Warnings...............................................93
Index........................................................................95
Contents
v
Preface
The ADAC Ultra2 S466 PCI RAID Controller supports all single
ended and low-voltage differential (LVD) SCSI devices on an
Ultra and Wide SCSI channel with data transfer rates up to 80
MB/s (Megabytes per second). This manual describes ADAC
Ultra2 S466.
Limited Warranty The buyer agrees if this product proves to be defective, that
Gateway is only obligated to repair or repl ace this product at
Gateway’s discretion according to the terms and conditions of the
warranty registration card that accompani es t his product.
Gateway shall not be liable in tort or contract for any loss or
damage, direct, incidental or consequential resulting from the use
of this product. Please see the Warranty Registration Card
shipped with this product for full warranty details.
Limitations of Liability Gateway, Inc. shall in no event be held liable for any loss,
expenses, or damages of any kind whatsoever, whether direct,
indirect, incidental, or consequential (whether arising from the
design or use of this product or the support materials provided
with the product). No action or proceeding against Gateway may
be commenced more than two years after the delivery of product
to Licensee of Licensed Software.
Licensee agrees to defend and indemnify Gateway from any and
all claims, suits, and liabilities (including attorney’s fees) arising
out of or resulting from any actual or alleged act or omission on
the part of Licensee, its authorized third parties, employees, or
agents, in connection with the distribution of Licensed Software
to end-users, including, without limitation, claims, suits, and
liability for bodily or other injuries to end-users resulting from
use of Licensee’s product not caused solely by faults in Licensed
Software as provided by Gateway to Licensee.
Cont’d
Preface vii
Preface, Continued
Package Contents You should have received:
• a ADAC Ultra2 S466 PCI RAID Controller,
• a ADAC Ultra2 S466 Hardware Guide,
• a ADAC Ultra2 S466 Configuration Software Guide,
• a ADAC Ultra2 S466 Operating System Drivers
Guide,
• software license agreement,
• diskette(s) with the ADAC Ultra2 S466 software, and
• a warranty registration card.
Technical Support If you need help insta lling, configuring, or running the
ADAC Ultra2 S466 PCI RAID Controller, call your
Gateway OEM Technical Support representative. For the
current number, refer to the Assistance Resources
Brochure that was included with your system. Before you
call, please complete the ADAC Ultra2 S466 Problem
Report form on the next page.
Web Site We invite you to access the Gateway world wide web site
at:
http://www.gateway.com.
ADAC Ultra2 S466 Hardware Guide
viii
ADAC Ultra2 S466 Problem Report Form
Customer Information ADAC Ultra2 S466 Information
Name Today’s Date
Company Date of Purchase
Address Invoice Number
City/State Serial Number
Country
email address Cache Memory
Phone Firmware Version
Fax BIOS Version
System Information
Motherboard: BIOS manufacturer:
Operating System: BIOS Date:
Op. Sys. Ver.: Video Adapter:
ADAC Ult ra2 S4 66
Driver Ver.:
Network Card: System Memory:
Other disk controllers
installed:
Description of problem:
Steps necessary to re-create problem:
1.
CPU Type/Speed:
Other adapter cards
installed:
2.
3.
4.
Logical Drive Configuration
Logical
Drive
RAID
Level
Stripe
Size
Logical Drive
LD1
LD2
LD3
LD4
LD5
LD6
LD7
LD8
Preface
Size
Cache
Policy
Read
Policy
Write
Policy
# of Physical
Drives
ix
Physical Device Layout
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
ADAC Ultra2 S466 Hardware Guide
x
Channel 1
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Target ID
Device Type
Logical Drive Number/ Drive Number
Manufacturer/Model Number
Firmware level
Channel 1
Preface
xi
Preface, Continued
Disclaimer This manual describes the operation of the Gateway ADAC
Ultra2 S466 Disk Array Controller. Although efforts have been
made to assure the accuracy of the information contained here,
Gateway expressly disclaims liability for any error in this
information, and for damages, whether direct, indirect, special,
exemplary, consequential or otherwise, that may result from such
error, including but not limited to the loss of profits resulting
from the use or misuse of the manual or information contained
therein (even if Gateway has been advised of the possibility of
such damages). Any questions or comments regarding this
document or its contents should be addressed to Gateway at the
address shown on the cover.
Gateway provides this publication “as is” without warranty of
any kind, either expressed or implied, including, but not limited
to, the implied warranties of merchantability or fitness for a
specific purpose.
Some states do not allow disclaimer of express or implied
warranties or the limitation or exclusion of liability for indirect,
special, exemplary, incident al or consequenti al damages in
certain transactions; therefore, this statement may not apply to
you. Also, you may have other rights which vary from
jurisdiction to jurisdiction.
This publication could include technical inaccuraci es or
typographical errors. Changes are periodically made to the
information herein; these changes will be incorporated in new
editions of the publication. Gateway may make improvements
and/or revisions in the product(s) and/or the program(s)
described in this publication at any time.
Requests for technical information about Gateway products
should be made to your Gateway representative.
ADAC Ultra2 S466 Hardware Guide
xii
FCC Regulatory Statement
This device complies with Part 15 of the FCC Rules. Operation is subject to
the following two conditions: (1) this device may not cause harmful
interference, and (2) this device must accept any interference received,
including interference that may cause undesired operation.
Warning: Changes or modifications to this unit not expressly approved
by the party responsible for compliance could void the user’s authority
to operate the equipment.
Note: This equipment has been tested and found to comply with the limits
for a Class B digital device, pursuant to Part 15 of the FCC Rules. These
limits are designed to provide reasonable protection against harmful
interference in a residential installation. This equipment generates, uses and
can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not
occur in a specific installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by
turning the equipment off and on, try to correct the interference by one or
more of the following measures:
1) Reorient or relocate the receiving antenna.
2) Increase the separation between the equipment and
the receiver.
3) Connect the equipment into an outlet on a circuit different from
that to which the receiver is connected.
4) Consult the dealer or an experienced radio/TV technician
for help.
Shielded interface cables must be used with this product to ensure
compliance with the Cla ss B FCC limits.
Gateway ADAC Ultra2 S466 PCI RAID Controller
Model Number: Series 466
FCC ID Number: IUESER466
Preface
xiii
Disclaimer
Gateway only certifies that this product will work correctly when this
product is used with the same jumper settings, the same system
configuration, the same memory module parts, and the same
peripherals that were tested by Gateway with this product. The
complete list of tested jumper settings, system configurations,
peripheral devices, and memory modules are documented in the
Gateway Compatibility Report for this product. Call your Gateway
sales representative for a copy of the Compatibility Report for this
product.
ADAC Ultra2 S466 Hardware Guide
xiv
1 Overview
The ADAC Ultra2 S466 PCI RAID controller is a high
performance intelligent PCI-to-SCSI host adapter with
RAID control capabilities. The ADAC Ultra2 S466
provides reliability, high performance, and fault-tolerant
disk subsystem management. The ADAC Ultra2 S466 is an
entry level-to mid-range RAID controller solution. ADAC
Ultra2 S466 offers a cost-effective way to implement
RAID in a server. The ADAC Ultra2 S466 has an Ultra
and Wide SCSI channel supporting data transfer rates up to
80 Megabytes per second (MB/s) per channel. The SCSI
channel supports up to fifteen non-Ultra SCSI devices.
ADAC Ultra2 S466 Features ADAC Ultra2 S466 features:
• provides a high performance I/O migration path while
preserving existing PCI-SCSI software,
• Performs SCSI data transfers up to 80 MB/s,
• performs synchronous operation on a wide LVD SCSI bus,
• allows up to 15 LVD SCSI devices on the wide bus,
• includes an Intel® i960RP that performs RAID calculations
and routing and
• supports 4, 8, 16, 32, 64, or 128 MB of Fast Page Mode or
EDO DRAM cache memory in a SIMM socket used for read
and write-back caching and RAID 5 parity generation.
SCSI Channel The ADAC Ultra2 S466 upgrade card includes one Fast-20
SCSI channel. The channel is powered by a Symbios Logic
53C895 (Fast-40) SCSI processor.
NVRAM and Flash ROM A 32 KB x 8 NVRAM stores RAID system
configuration information. The ADAC Ultra2 S466
firmware is stored in flash ROM for easy upgrade.
SCSI Connectors ADAC Ultra2 S466 has one ultra high density 68-pin
external connector for external storage subsystem and one
high density 68-pin internal co nnector.
Chapter 1 Overview
1
Single Ended and Differential SCSI Buses
The SCSI standard defines two electrical buses:
• a single ended bus and
• low-voltage differential bus.
Maximum Cable Length for SCSI Standards
Standard Single ended LVD Maximum Number
of Drives
SCSI I 6 m 12 m 7
Fast SCSI 6 m 12 m 7
Fast Wide SCSI 6 m 12 m 15
Ultra SCSI 1.5 m 12 m 7
Ultra SCSI 3 m 12 m 3
Wide Ultra SCSI 12 m 15
Wide Ultra SCSI 1.5 m 12 m 7
Wide Ultra SCSI 3 m 12 m 3
Ultra 2 SCSI 25 m 1
Ultra 2 SCSI 12 m 7
Wide Ultra 2 SCSI 25 m 1
Wide Ultra 2 SCSI 12 m 15
SCSI Bus Widths and Maximum Throughput
SCSI Standard SCSI B us Width SCSI Throughput
SCSI I 8 bits 5 MB/s
Fast SCSI 8 bits 10 MB/s
Fast Wide SCSI 16 bits 20 MB/s
Ultra SCSI 8 bits 20 MB/s
Wide Ultra SCSI 16 bits 40 MB/s
Ultra 2 SCSI 8 bits 40 MB/s
Wide Ultra 2 SCSI 16 bits 80 MB/s
ADAC Ultra2 S466 Hardware Guide
2
Documentation
The ADAC Ultra2 S466 documentation set includes:
Using ADAC Ultra2 S466 Manuals This manual contains the RAI D
overview, RAID planning, and RAID system configuration
information you will need first. Read the ADAC Ultra2
S466 Hardware Guide first.
ADAC Ultra2 S466 Configuration Software Guide This manual describes
the software configuration utilities that configure and
modify RAID systems.
ADAC Ultra2 S466 Operating System Drivers Guide This manual provides
detailed information about installing the ADAC Ultra2
S466 operating system drivers.
Chapter 1 Overview
3
ADAC Ultra2 S466 Block Diagram
ADAC Ultra2 S466 Hardware Guide
4
2 Introduction to RAID
RAID (Redundant Array of Independent Disks) is an array
of multiple independent hard disk drives that provide high
performance and fault tolerance. A RAID disk subsystem
improves I/O performance over a computer using only a
single drive. The RAID array appears to the host computer
as a single storage unit or as multiple logical units. I/O is
expedited because several disks can be accessed
simultaneously. RAID systems improve data storage
reliability and fault tolerance compared to single-drive
computers. Data loss because of a disk drive failure can be
recovered by reconstructing missing data from the
remaining data and parity drives.
RAID Benefits
RAID has gained popularity because it: improves I/O
performance, and increases storage subsystem reliability.
RAID provides data security through fault tolerance and
redundant data storage. The ADAC Ultra2 S466
management software configures and monitors RAID disk
arrays.
Improved I/O Although disk drive capabilities have improved drastically,
actual performance has improved only three to four times
in the last decade. Computing performance has improved
over 50 times during the same time period.
Increased Reliability The electromechanical components of a disk
subsystem operate more slowly, require more power, and
generate more noise and vibration than electronic devices.
These factors reduce the reliability of data stored on disks.
Chapter 2 Introduction to RAID
5
In This Chapter
The following topics are discussed:
Major Topic Subtopic turn to
Host-based solution page 7
RAID overview page 8
Consistency check page 8
Fault tolerance page 8
Disk striping page 9
Disk spanning page 10
Disk mirroring page 11
Parity page 12
Hot spares page 13
Disk rebuilds page 14
RAID levels page 19
Selecting a RAID level page 20
RAID 0 page 2 1
RAID 1 page 2 2
RAID 3 page 2 3
RAID 5 page 2 5
RAID 10 page 26
RAID 30 page 27
RAID 50 page 28
ADAC Ultra2 S466 Hardware Guide
6
ADAC Ultra2 S466 – Host-Based RAID Solution
RAID products are either:
• host-based or
• SCSI-to-SCSI.
The ADAC Ultra2 S466 controller is a host-based RAID
solution. ADAC Ultra2 S466 is a PCI adapter card that is
installed in any available PCI expansion slot in a host
system.
Host-Based A host-based RAID product puts all of the RAID
intelligence on an adapter card that is installed in a network
server. A host-based RAID product provides the best
performance. ADAC Ultra2 S466 is part of the file server,
so it can transmit data directly across the computer’s buses
at data transfer speeds up to 132 MB/s.
The available sequential data transfer rate is determined by
the following factors:
the sustained data transfer rate on the motherboard
•
PCI bus,
the sustained data transfer rate on the i960RP PCI to
•
PCI bridge,
the sustained data transfer rate of the SCSI controller,
•
the sustained data transfer rate of the SCSI devices,
•
the number of SCSI channels, and
•
the number of SCSI disk drives.
•
Host-based solutions must provide operating systemspecific drivers.
SCSI-to-SCSI A SCSI-to-SCSI RAID product puts the RAID intelligence
inside the RAID chassis and uses a plain SCSI Host
Adapter installed in the network server. The data transfer
rate is limited to the bandwidth of the SCSI channel. A
SCSI-to-SCSI RAID product that has two wide SCSI
channels that operate at speeds up to 80 MB/s must
squeeze the data into a single wide SCSI (40 MB/s)
channel back to the host computer.
In SCSI-to-SCSI RAID products, the hard drive subsystem
uses only a single SCSI ID, which allows you to connect
multiple drive subsystems to a single SCSI controller.
Chapter 2 Introduction to RAID
7
RAID Overview
RAID (Redundant Array of Independent Disks) is a
collection of specifications that describe a system for
ensuring the reliability and stability of data stored on large
disk subsystems. A RAID system can be implemented in a
number of different versions (or RAID Levels). The
standard RAID levels are 0, 1, 3, and 5. ADAC Ultra2
S466 supports all standard RAID levels and RAID levels
10, 30, and 50, special RAID versions supported by ADAC
Ultra2 S466.
Consistency Check
In RAID, check consistency verifies the correctness of
redundant data in an array. For example, in a system with
dedicated parity, checking consistency means computing
the parity of the data drives and comparing the results to
the contents of the dedicated parity drive.
Fault Tolerance
Fault tolerance is achieved through cooling fans, p ower
supplies, and the ability to hot swap drives. ADAC Ultra2
S466 provides hot swapping through the hot spare feature.
A hot spare drive is an unused online available drive that
ADAC Ultra2 S466 instantly plugs into the system when
an active drive fails.
After the hot spare is automatically moved into the RAID
subsystem, the failed drive is automatically rebuilt. The
RAID disk array continues to handle request while the
rebuild occurs.
ADAC Ultra2 S466 Hardware Guide
8
Disk Striping
Disk striping writes data across multiple disk drives instead
of just one disk drive. Disk striping involves pa rtitioning
each drive storage space into stripes that can vary in size
from 2 KB to 128 KB. These stripes are interleaved in a
repeated sequential manner. The combined storage space is
composed of stripes from each drive. ADAC Ultra2 S466
supports stripe sizes of 2 KB, 4 KB, 8 KB, 16 KB, 32 KB,
64 KB, or 128 KB.
For example, in a four-disk system using only disk striping
(as in RAID level 0), segment 1 is written to disk 1,
segment 2 is written to disk 2, and so on. Disk striping
enhances performance because multiple drives are
accessed simultaneously; but disk striping does not provide
data redundancy.
Stripe Width Stripe width is the number of disks involved in an array
where striping is implemented. For example, a four-disk
array with disk striping has a stripe width of four.
Stripe Size The stripe size is the length of the interleaved data
segments that ADAC Ultra2 S466 writes across multiple
drives. ADAC Ultra2 S466 supports stripe sizes of 2 KB, 4
KB, 8 KB, 16 KB, 32 KB, 64 KB, or 128 KB.
Chapter 2 Introduction to RAID
9
Disk Spanning
Disk spanning allows multiple disk drives to function like
one big drive. Spanning overcomes lack of disk space and
simplifies storage management by combining existing
resources or adding relatively inexpensive resources. For
example, four 400 MB disk drives can be combined to
appear to the operating system as one single 1600 MB
drive.
Spanning alone does not provide reliability or performance
enhancements. Spanned logical drives must have the same
stripe size and must be contiguous. In the following
graphic, RAID 1 array is turned into a RAID 10 array.
Spanning for RAID 10, RAID 30, or RAID 50
Level Description
10 Configure RAID 10 by spanning two contiguous RAID 1 logical drives.
The RAID 1 logical drives must have the same stripe size.
30 Configure RAID 30 by spanning two contiguous RAID 3 logical drives.
The RAID 3 logical drives must have the same stripe size.
50 Configure RAID 50 by spanning two contiguous RAID 5 logical drives.
The RAID 5 logical drives must have the same stripe size.
Note:
10
Spanning two contiguous RAID 0 logical drives does not produce a new
RAID level or add fault tolerance. It does increase the size of the lo gical
volume and improves performance by doubling the number of spindles.
ADAC Ultra2 S466 Hardware Guide
Disk Mirroring
With mirroring (used in RAID 1), data written to one disk
drive is simultaneously written to another disk drive. If one
disk drive fails, the contents of the other disk drive can be
used to run the system and reconstruct the failed drive. The
primary advantage of disk mirroring is that it provides
100% data redundancy. Since the contents of the disk drive
are completely written to a second drive, it does not matter
if one of the drives fails. Both drives contain the same data
at all times. Either drive can act as the operational drive.
Disk mirroring provides 100% redundancy, but is
expensive because each drive in the system must be
duplicated.
Chapter 2 Introduction to RAID
11
Parity
Parity generates a set of redundancy data from two or more
parent data sets. The redundancy data can be used to
reconstruct one of the parent data sets. Parity data does not
fully duplicate the parent data sets. In RAID, this method is
applied to entire drives or stripes across all disk d rives in
an array. The types of parity are:
Type Description
Dedicated Parity The parity of the data on two or more disk drives is
stored on an additional disk.
Distributed
Parity
The parity data is distributed across all drives in the
system.
If a single disk drive fails, it can be rebuilt from the parity
and the data on the remaining drives.
RAID level 3 combines dedicated parity with disk striping.
The parity disk in RAID 3 is the last logical drive in a
RAID set.
RAID level 5 combines distributed parity with disk
striping. Parity provides redundancy for one drive failure
without duplicating the contents of entire disk drives, but
parity generation can slow the write process. A dedicated
parity scheme during normal read/write operations is
shown below:
ADAC Ultra2 S466 Hardware Guide
12
Hot Spares
Hot spares are only employed in arrays with redundancy, for
A hot spare connected to a specific ADAC Ultra2 S466
controller can only be used to rebuild a drive that is
A hot spare is an extra, unused disk drive that is part of the
disk subsystem. It is usually in standby mode, ready for
service if a drive fails. Hot spares permit you to replace
failed drives without system shutdown or user intervention.
ADAC Ultra2 S466 implements automatic and transparent
rebuilds using hot spare drives, providing a high degree of
fault tolerance and zero downtime. The ADAC Ultra2
S466 RAID Management software allows you to specify
physical drives as hot spares. When a hot spare is needed,
the ADAC Ultra2 S466 controller assigns the hot spare that
has a capacity closest to and at least as great as that of the
failed drive to take the place of the failed drive.
Important
example, RAID levels 1, 3, 5, 10, 30, and 50.
connected to the same controller.
Chapter 2 Introduction to RAID
13
Disk Rebuild
You rebuild a disk drive by recreating the data that had
been stored on the drive before the drive failed.
Rebuilding can be done only in arrays with data
redundancy such as RAID level 1, 3, 5, 10, 30, and 50.
Standby (warm spare) rebuild is employed in a mirrored
(RAID 1) system. If a disk drive fails, an identical drive is
immediately available. The primary data source disk drive
is the original disk drive.
A hot spare can be used to rebuild disk drives in RAID 1,
3, 5, 10, 30, or 50 systems. If a hot spare is not available,
the failed disk drive must be replaced with a new disk drive
so that the data on the failed drive can be rebuilt.
The ADAC Ultra2 S466 controller automatically and
transparently rebuilds failed drives with user-definable
rebuild rates. If a hot spare is available, the rebuild starts
automatically when a drive fails. ADAC Ultra2 S466
automatically restarts the system and the rebuild if the
system goes down during a rebuild.
Rebuild Rate The rebuild rate is the fraction of the compute cycles
dedicated to rebuilding failed drives. A rebuild rate of 100
percent means the system is totally dedicated to rebuilding
the failed drive.
The ADAC Ultra2 S466 rebuild rate can be configured
between 0% and 100%. At 0%, the rebuild is only done if
the system is not doing anything else. At 100%, the rebuild
has a higher priority than any other system activity.
Physical Array A RAID array is a collection of physical disk drives
governed by the RAI D management software. A RAID
array appears to the host computer as one or more logical
drives.
ADAC Ultra2 S466 Hardware Guide
14
Logical Drive
Hot Swap
A logical drive is a partition in a physical array of disks
that is made up of contiguous data segments on the
physical disks. A logical drive can consist of any of the
following:
• an entire physical array,
• more than one entire physical array,
• a part of an array,
• parts of more than one array, or
• a combination of any two of the above conditions.
A hot swap is the manual replacement of a defective
physical disk unit while the computer is still running. When
a new drive has been installed, you must issue a command
to rebuild the drive.
Chapter 2 Introduction to RAID
15
SCSI Drive States
A SCSI disk drive can be in one of these states:
State Description
Online
(ONLIN)
Ready
(READY)
Hot Spare
(HOTSP)
Fail
(FAIL)
Rebuild
(REB)
The drive is functioning normally and is a part of a configured
logical drive.
The drive is functioning normally but is not part of a configured
logical drive and i s not designated as a hot spare.
The drive is powered up and ready for use as a spare in case an
online drive fails.
A fault has occurred in the drive placing it out of service.
The drive is being rebuilt with data from a failed drive.
Logical Drive States
State Description
Optimal The drive operating condition is good. All configured drives are
online
Degraded The drive operating condition is not optimal. One of the
configured drives has failed or is offline.
Failed The drive has failed.
Offline The drive is not available to ADAC Ultra2 S466.
ADAC Ultra2 S466 Hardware Guide
16
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