Protecting your system and data
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. VxVM 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:
-
Place the disk containing the root file system (the root or boot disk) under VxVM control through encapsulation. Encapsulation converts the
root
and swap
devices to volumes (rootvol
and swapvol
).
-
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 maximum availability of the system, create mirrors for the rootvol
, swapvol
, usr
, and var
volumes. For more information, see the Veritas Volume Manager Troubleshooting Guide.
-
Use mirroring to protect data against loss from a disk failure. To preserve data, create and use mirrored volumes that have at least two data plexes. The plexes must be on different disks. If a disk failure causes a plex to fail, the data in the mirrored volume still exists on the other disk.
-
Leave the VxVM hot-relocation feature enabled to detect disk failures automatically. It will notify you of the nature of the failure, attempt to relocate any affected subdisks that are redundant, and initiate recovery procedures. Configure at least one hot-relocation spare disk in each disk group. This will allow sufficient space for relocation in the event of a failure.
If the root
disk is mirrored, hot-relocation can automatically create another mirror of the root
disk if the original root
disk fails. The rootdg must contain enough contiguous spare or free space for the volumes on the root disk (rootvol
and swapvol
volumes require contiguous disk space).
-
Use the DRL feature to speed up recovery of mirrored volumes after a system crash. Make sure that each mirrored volume has at least one log subdisk.
Note
rootvol
, swapvol
, and usr
volumes cannot be DRL volumes.
-
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.
-
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.