Several "best practice" rules enable you to check that your storage configuration has the resilience to withstand a disk failure or a system failure.
To check whether more than one RAID-5 log exists on the same physical disk, run rule vxse_disklog
.
RAID-5 log mirrors for the same physical volume should be located on separate physical disks to ensure redundancy. More than one RAID-5 log on a disk also makes the recovery process longer and more complicated.
To check whether large mirror volumes (larger than 1GB) have an associated dirty region log (DRL), run rule vxse_drl1
.
Creating a DRL speeds recovery of mirrored volumes after a system crash. A DRL tracks those regions that have changed and uses the tracking information to recover only those portions of the volume that need to be recovered. Without a DRL, recovery is accomplished by copying the full contents of the volume between its mirrors. This process is lengthy and I/O intensive.
See "Preparing a volume for DRL and instant snapshots" on page 285.
To check whether a large mirrored volume has a mirrored DRL log, run rule vxse_drl2
.
Mirroring the DRL log provides added protection in the event of a disk failure.
See "Preparing a volume for DRL and instant snapshots" on page 285.
To check whether a RAID-5 volume has an associated RAID-5 log, run rule vxse_raid5log1.
In the event of both a system failure and a failure of a disk in a RAID-5 volume, data that is not involved in an active write could be lost or corrupted if there is no RAID-5 log.
See "Adding a RAID-5 log" on page 293.
To check that the size of RAID-5 logs falls within the minimum and maximum recommended sizes, run rule vxse_raid5log2.
The recommended minimum and maximum sizes are 64MB and 1GB respectively. If vxse_raid5log2
reports that the size of the log is outside these boundaries, adjust the size by replacing the log.
To check that the RAID-5 log of a large volume is mirrored, run the vxse_raid5log3
rule.
A mirror of the RAID-5 log protects against loss of data due to the failure of a single disk. You are strongly advised to mirror the log if vxse_raid5log3
reports that the log of a large RAID-5 volume does not have a mirror.
See "Adding a RAID-5 log" on page 293.