VERITAS Volume Manager 3.1 Administrator's Guide

Volume Manager Operations
Hot-Relocation
Chapter 3 103
Hot-Relocation
NOTE You may need an additional license to use this feature.
Hot-relocation allows a system to automatically react to I/O failures
on redundant (mirrored or RAID-5) Volume Manager objects and restore
redundancy and access to those objects. The Volume Manager detects I/O
failures on objects and relocates the affected subdisks. The subdisks are
relocated to disks designated as spare disks and/or free space within
the disk group. The Volume Manager then reconstructs the objects that
existed before the failure and makes them redundant and accessible
again.
When a partial disk failure occurs (that is, a failure affecting only some
subdisks on a disk), redundant data on the failed portion of the disk is
relocated. Existing volumes on theunaffected portions of the disk remain
accessible.
NOTE Hot-relocation is only performed for redundant (mirrored or RAID-5)
subdisks on afailed disk. Nonredundant subdisks on afailed disk are not
relocated, but the system administrator is notified of the failure.
How Hot-Relocation Works
The hot-relocation feature is enabled by default. No system
administrator action is needed to start hot-relocation when a failure
occurs.
The hot-relocation daemon, vxrelocd, monitors Volume Manager for
events that affect redundancy and performs hot-relocation to restore
redundancy. The vxrelocd daemon also notifies the system
administrator (via electronic mail) of failures and any relocation and
recovery actions. See the vxrelocd(1M) manual page for more
information on vxrelocd.
The vxrelocd daemon starts during system startup and monitors the
Volume Manager for failures involving disks, plexes, or RAID-5 subdisks.