Seagate ST34572WC Specifications download pdf (Page 6)

reinstall a minimal system, restore a backup, and be back online within three hours of diagnosis and

replacement of hardware.

Three disks in the root volume group are better than two, because of quorum restrictions. With a two-disk

root volume group, a loss of one disk can require you to override quorum to activate the volume group; if

you must reboot to replace the disk, you must interrupt the boot process and use the –lq boot option. If

you have three disks in the volume group, and they are isolated from each other such that a hardware

failure only affects one of them, then failure of only one disk enables the system to maintain quorum.

• Keep your other volume groups small, if possible. Many small volume groups are preferable to a few

large volume groups, for most of the same reasons mentioned previously. In addition, with a very large

volume group, the impact of a single disk failure can be widespread, especially if you must deactivate the

volume group. With a smaller volume group, the amount of data that is unavailable during recovery is

much smaller, and you will spend less time reloading from backup. If you are moving disks between

systems, it is easier to track, export, and import smaller volume groups. Several small volume groups often

have better performance than a single large one. Finally, if you ever have to recreate all the disk layouts,

a smaller volume group is easier to map.

Consider organizing your volume groups such that the data in each volume group is dedicated to a

particular task. If a disk failure makes a volume group unavailable, then only its associated task is affected

during the recovery process.

• Maintain adequate documentation of your I/O and LVM configuration, specifically the outputs from the

following commands:

Command Scope Purpose

ioscan –f

Print I/O configuration

lvlnboot -v

Print information on root, boot, swap, and

dump logical volumes

vgcfgrestore –l

for all volume groups

Print volume group configuration from

backup file

vgdisplay –v

for all volume groups

Print volume group information, including

status of logical volumes and physical

volumes

lvdisplay –v

for all logical volumes

Print logical volume information, including

mapping and status of logical extents

pvdisplay –v

for all physical volumes

Print physical volume information,

including status of physical extents

With this information in hand, you or your HP support representative may be able to reconstruct a lost

configuration, even if the LVM disks have corrupted headers. A hard copy is not required or even

necessarily practical, but accessibility during recovery is important and you should plan for this.

• Make sure that your LVM configuration backups stay up-to-date. Make an explicit configuration backup

using the vgcfgbackup command immediately after importing any volume group or activating any

shared volume group for the first time. Normally, LVM backs up a volume group configuration whenever

you run a command to change that configuration; if an LVM command prints a warning that

vgcfgbackup failed, be sure to investigate it.

While this list of preparatory actions does not keep a disk from failing, it makes it easier for you to deal with

failures when they occur.

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Seagate ST34572WC Specifications Page 6

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