VERITAS Volume Manager 4.1 Administrator's Guide

Administering Hot-Relocation

How Hot-Relocation works

Chapter 9 333

any available free space in the disk group in which the failure occurs. If

there is not enough spare disk space, a combination of spare space and

free space is used.

The free space used in hot-relocation must not have been excluded from

hot-relocation use. Disks can be excluded from hot-relocation use by

using vxdiskadm, vxedit or the VERITAS Enterprise Administrator

(VEA).

You can designate one or more disks as hot-relocation spares within each

disk group. Disks can be designated as spares by using vxdiskadm,

vxedit, or the VEA. Disks designated as spares do not participate in the

free space model and should not have storage space allocated on them.

When selecting space for relocation, hot-relocation preserves the

redundancy characteristics of the VxVM object to which the relocated

subdisk belongs. 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 VxVM ensures that the disk space used by

the failed subdisk is not recycled as free space.