HP Xw8400 Software RAID in Linux Workstations
HP Xw8400 - Workstation - 4 GB RAM Manual
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UPC - 883585271085
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- HP Xw8400 | Software RAID in Linux Workstations - Page 1
Software RAID in Linux Workstations Mini-White Paper Introduction...3 RAID Basics ...3 RAID Overview ...3 Software RAID in Linux ...3 Performance and Bottlenecks ...4 RAID Levels ...4 RAID-Linear: Concatenating Disks...4 RAID-0: Striping ...4 RAID-1: Mirroring...5 RAID-2: Error Checking and - HP Xw8400 | Software RAID in Linux Workstations - Page 2
The Persistent Superblock ...15 Chunk Sizes ...15 Swap Space in a RAID Configuration 16 Boot Partitions in a Mirrored RAID Configuration 16 Software RAID and LVM ...19 - HP Xw8400 | Software RAID in Linux Workstations - Page 3
RAID on Linux workstations, and information regarding disk failure, recovery, and other information pertaining to running software RAID on a Linux system. Please note that while BIOS messages may refer to hardware RAID, hardware RAID is not supported by HP Linux workstations. RAID Basics RAID - HP Xw8400 | Software RAID in Linux Workstations - Page 4
for failed drives in software RAID requires only a minimum amount of work. Hardware RAID is not supported by HP Linux workstations. Performance and Bottlenecks Disk I/O bandwidth is typically limited by the system's bus speeds, the disk controller, and the disks themselves. Each generation - HP Xw8400 | Software RAID in Linux Workstations - Page 5
Typically performance is sacrificed for recovery of data. Because data is mirrored, only half of the physical space is utilized, and data must be replicated to multiple disks, marginally increasing write times. Software RAID-1 is supported by HP Linux workstations. Figure 2. Efficiency of Software - HP Xw8400 | Software RAID in Linux Workstations - Page 6
very small and drive spindles are carefully synchronized. RAID-5 is generally preferred, and RAID-3 is very seldom used these days. Software RAID-3 is not supported by HP Linux workstations. RAID-4: Block-Level Striping with Parity Disk RAID-4 attempts to add error checking and recovery to RAID-3 by - HP Xw8400 | Software RAID in Linux Workstations - Page 7
must be configured manually. Software RAID-10 is the only additional RAID level supported by HP Linux workstations. Please note that while the Linux kernel allows for RAID-linear, -0, -1, -4, -5, and nested RAID levels, HP only provides support for RAID-0, 1, 5, and 10. RAID Configuration Strategies - HP Xw8400 | Software RAID in Linux Workstations - Page 8
but data protection is not as big a factor. • If it is necessary to have backup drives available at all time so there is no loss of data, even in case of a disk failure, a RAID-1 setup using several physical hard disks would provide a good degree of redundancy so that no critical data is lost. This - HP Xw8400 | Software RAID in Linux Workstations - Page 9
create a new partition. 5. From the File System Type menu, choose "Software RAID." 6. Select one physical disk to create the partition on. 7. Choose the size of the partition. 8. Click OK. Figure 5. Disk Setup 9. Repeat steps 4-8 until all necessary software RAID partitions are created. 10. From the - HP Xw8400 | Software RAID in Linux Workstations - Page 10
Anaconda installer only supports RAID-0, RAID-1, and RAID-5. Other levels or nested RAID must be configured manually after installation. If you are creating a nested RAID array, you can either configure the "bottom" RAID level (for example, the RAID-1 array in the case of nested RAID-10) in Anaconda - HP Xw8400 | Software RAID in Linux Workstations - Page 11
The GRUB and LILO boot loaders only support booting to RAID-1, or no RAID at all. If you wish to use a RAID level other than RAID-1, you must put the /boot partition on a non-RAID part of the filesystem. Manual Setup of Software RAID Data Partitions While HP recommends using the above method to set - HP Xw8400 | Software RAID in Linux Workstations - Page 12
commands needed to set up each of the basic RAID configurations supported by HP. RAID-0 /etc/raidtab file: raiddev /dev/md0 raid-level nr-raid-disks nr-spare-disks persistent-superblock chunk-size device raid-disk device raid-disk 0 2 0 1 4 /dev/hda1 0 /dev/hdb1 1 Command: mdadm -Cv /dev/md0 - HP Xw8400 | Software RAID in Linux Workstations - Page 13
raid-disk device raid-disk 0 2 0 4 /dev/sda1 0 /dev/sdb1 1 raiddev /dev/md1 raid-level nr-raid-disks nr-spare-disks chunk-size device raid-disk device raid-disk 0 2 0 4 /dev/sdc1 0 /dev/sdd1 1 raiddev /dev/md2 raid-level nr-raid-disks nr-spare-disks chunk-size device raid-disk device raid-disk - HP Xw8400 | Software RAID in Linux Workstations - Page 14
, and your /etc/raidtab file will differ based on your specific hard drive configuration. Disk Failure and Recovery Spare Disks and Disk Failure Spare disks are disks that do not take part in the RAID configuration until one of the active disks fails. At that point, the failed device is marked as - HP Xw8400 | Software RAID in Linux Workstations - Page 15
system administrator. There are many other monitoring systems available for Linux software RAID as well. Multiple Disk Failure In the case of a temporary failure of multiple disks, such as a disk controller wanted to boot on a RAID. The persistent superblock solves these problems. When an array is - HP Xw8400 | Software RAID in Linux Workstations - Page 16
configuration is required to make sure that all hard drives in a RAID-1 array will be bootable in case of failure. In this case, you will need to create a bootable partition on each physical hard disk that will be part of the RAID-1 array. This is easiest when done during the original installation - HP Xw8400 | Software RAID in Linux Workstations - Page 17
same partition number for each of the bootable partitions. For example, if your primary /boot partition resides on /dev/sda1, you should create a partition called /boot1, located on /dev/sdb1, and so on for each hard disk. 5. Create a bootable partition on each disk that will be in the RAID-1 array - HP Xw8400 | Software RAID in Linux Workstations - Page 18
to boot to any of the other drives in the RAID array if the first disk should fail. Tip: While you do not need to have /boot mounted for the system to boot normally, you will need to mount it if you are running a kernel update. After the update is complete, repeat these steps to mirror - HP Xw8400 | Software RAID in Linux Workstations - Page 19
the system or entering into maintenance/standalone mode. In general, it adds a layer of abstraction between filesystem mount points such as / or /usr, and hard disk devices such as /dev/hda1 or /dev/sdb2. The benefit of using LVM is the flexibility of being able to add or remove physical hard drives
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Software RAID in Linux Workstations
Mini-White Paper
Introduction
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3
RAID Basics
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3
RAID Overview
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3
Software RAID in Linux
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3
Performance and Bottlenecks
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4
RAID Levels
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4
RAID-Linear: Concatenating Disks
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4
RAID-0: Striping
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4
RAID-1: Mirroring
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5
RAID-2: Error Checking and Correction
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6
RAID-3: Byte-Level Striping with Parity Disk
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6
RAID-4: Block-Level Striping with Parity Disk
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6
RAID-5: Block-Level Striping with Distributed Parity
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6
Additional RAID Levels
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7
RAID Configuration Strategies
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7
Performance
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7
Capacity versus Fault-Tolerance
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7
Cost
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7
RAID Performance Considerations
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8
Configuring Red Hat Enterprise Linux with Software RAID
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8
Manual Setup of Software RAID Data Partitions
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11
Manual Configuration Examples
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12
RAID-0
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12
RAID-1
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12
RAID-5
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13
RAID-10
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13
Disk Failure and Recovery
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14
Spare Disks and Disk Failure
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14
Multiple Disk Failure
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15
Additional Configuration Information
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15