Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

499Configuring Veritas Volume Manager
Guidelines for configuring storage
Guidelines for configuring storage
A disk failure can cause loss of data on the failed disk and loss of access to your system.
Loss of access is due to the failure of a key disk used for system operations. Veritas
Volume Manager can protect your system from these problems.
To maintain system availability, data important to running and booting your system must
be mirrored. The data must be preserved so it can be used in case of failure.
The following are suggestions for protecting your system and data:
■ Perform regular backups to protect your data. Backups are necessary if all copies of a
volume are lost or corrupted. Power surges can damage several (or all) disks on your
system. Also, typing a command in error can remove critical files or damage a file
system directly. Performing regular backups ensures that lost or corrupted data is
available to be retrieved.
■ Place the disk containing the root file system (the root or boot disk) under Veritas
Volume Manager control. Mirror the root disk so that an alternate root disk exists for
booting purposes. By mirroring disks critical to booting, you ensure that no single
disk failure leaves your system unbootable and unusable. For more information, see
“Rootability” on page 102.
■ Use mirroring to protect data against loss from a disk failure. See “Mirroring
guidelines” on page 499 for details.
■ Use the DRL feature to speed up recovery of mirrored volumes after a system crash.
See “Dirty region logging guidelines” on page 500 for details.
■ Use striping to improve the I/O performance of volumes. See “Striping guidelines”
on page 501 for details.
■ Make sure enough disks are available for a combined striped and mirrored
configuration. At least two disks are required for the striped plex, and one or more
additional disks are needed for the mirror.
■ When combining striping and mirroring, never place subdisks from one plex on the
same physical disk as subdisks from the other plex.
■ Use logging to prevent corruption of recovery data in RAID-5 volumes. Make sure
that each RAID-5 volume has at least one log plex. See “RAID-5 guidelines” on
page 502 for details.
■ Leave the Veritas Volume Manager hot-relocation feature enabled. See “Hot-
relocation guidelines” on page 502 for details.
Mirroring guidelines
Refer to the following guidelines when using mirroring.