The volume Add Log procedure
adds the appropriate type of log to a mirrored or RAID-5 volume.
When used to add a Dirty Region Logging (DRL) log to a mirrored
volume, DRL uses this log to track the regions of the volume that
change due to I/O writes. If a system failure occurs, DRL uses the
information in the log to recover only the portions of the volume
that need recovery. This speeds up recovery time for mirrored volumes.
For DRL to be in effect, a mirrored volume must have at least
one DRL log. You can create additional DRL logs (on different disks)
to mirror the DRL information.
When used to add a log to a RAID-5 volume, the log speeds
up the resynchronization time for RAID-5 volumes after a system
failure. A RAID-5 log maintains a copy of the data and parity being
written to the volume at any given time. If a system failure occurs,
VxVM can "replay" the RAID-5 log to resynchronize
the volume. This copies the data and parity that was being written
at the time of failure from the log to the appropriate areas of
the RAID-5 volume. You can create multiple RAID-5 logs (on different
disks) to mirror the log information. Ideally, each RAID-5 volume
has at least two logs.
Select the mirrored volume or RAID-5 volume
to contain the log.
Select Actions > Log > Add.
By default the "Auto assign destination disks" option
will be selected. To manually assign the destination disks, select
the "Manually assign destination disks" option.
Available disks will appear in the left window. To add destination
disks, select them in the left window and click the Add button. To add all of the available disks, click the Add All button.
To remove destination disks, select them in the right window
and then click the Remove button. To remove all of the destination disks, click
the Remove All button.
Click Apply to create the Log then OK.
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 | NOTE: When a log is added to a mirrored volume, DRL is activated
for that volume. |
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