VERITAS Volume Manager 4.1 Administrator's Guide

Administering Hot-Relocation
How Hot-Relocation works
Chapter 9328
Step 1. vxrelocd informs the system administrator (and other nominated users,
see “Modifying the Behavior of Hot-Relocation” on page 349) by
electronic mail of the failure and which VxVM objects are affected. See
“Partial Disk Failure Mail Messages” on page 331 and “Complete Disk
Failure Mail Messages” on page 332 for more information.
Step 2. vxrelocd next determines if any subdisks can be relocated. vxrelocd
looks for suitable space on disks that have been reserved as
hot-relocation spares (marked spare) in the disk group where the failure
occurred. It then relocates the subdisks to use this space.
Step 3. If no spare disks are available or additional space is needed, vxrelocd
uses free space on disks in the same disk group, except those disks that
have been excluded for hot-relocation use (marked nohotuse). When
vxrelocd has relocated the subdisks, it reattaches each relocated
subdisk to its plex.
Step 4. Finally, vxrelocd initiates appropriate recovery procedures. For
example, recovery includes mirror resynchronization for mirrored
volumes or data recovery for RAID-5 volumes. It also notifies the system
administrator of the hot-relocation and recovery actions that have been
taken.
If relocation is not possible, vxrelocd notifies the system administrator
and takes no further action.
NOTE Hot-relocation does not guarantee the same layout of data or the same
performance after relocation. The system administrator can make
configuration changes after hot-relocation occurs.
Relocation of failing subdisks is not possible in the following cases:
• The failing subdisks are on non-redundant volumes (that is, volumes
of types other than mirrored or RAID-5).
• If you use vxdiskadm to remove a disk that contains subdisks of a
volume.
• There are insufficient spare disks or free disk space in the disk
group.
• The only available space is on a disk that already contains a mirror
of the failing plex.