VERITAS Volume Manager 3.1 Administrator's Guide

Volume Manager Operations
Hot-Relocation
Chapter 3 105
When selecting space for relocation, hot-relocation preserves the
redundancy characteristics of the Volume Manager object that the
relocated subdisk belongs to. For example, hot-relocation ensures that
subdisks from a failed plex are not relocated to a disk containing a
mirror of the failed plex. If redundancy cannot be preserved using any
available spare disks and/or free space, hot-relocation does not take
place. If relocation is not possible, the system administrator is notified
and no further action is taken.
From the eligible disks, hot-relocation attempts to use the disk that is
“closest” to the failed disk. The value of “closeness” depends on the
controller, target, and disk number of the failed disk. A disk on the same
controller as the failed disk is closer than a disk on a different controller;
a disk under the same target as the failed disk is closer than one on a
different target.
Hot-relocation tries to move all subdisks from a failing drive to the same
destination disk, if possible.
When hot-relocation takes place, the failed subdisk is removed from the
configuration database and Volume Manager ensures that the disk space
used by the failed subdisk is not recycled as free space.
For information on hot-relocation, see Chapter 4, “Disk Tasks.”
Modifying the vxrelocd Command
Hot-relocation is turned on as long as the vxrelocd procedure is
running. Leave hot-relocation turned on so that you can take advantage
of this feature if a failure occurs. Disabling this feature (because you do
not want the free space on some of your disks used for relocation)
prevents the vxrelocd procedure from starting at system startup time.
You can stop hot-relocation at any time by killing the vxrelocd process
(this should not be done while a hot-relocation attempt is in progress).
See “vxrelocd Command” for more information.
vxunreloc Unrelocate Utility
VxVM hot-relocation allows the system to automatically react to I/O
failures on a redundant VxVM object at the subdisk level and take
necessary action to make the object available again. This mechanism
detects I/O failures in a subdisk, relocates the subdisk, and recovers the
plex associated with the subdisk. After the disk has been replaced,