VERITAS Volume Manager 3.1 Administrator's Guide

Recovery
Detecting and Replacing Failed Disks
Chapter 8 347
Detecting and Replacing Failed Disks
This section describes how to detect disk failures and replace failed
disks. It begins with the hot-relocation feature, which automatically
attempts to restore redundant Volume Manager objects when a failure
occurs.
Hot-Relocation
NOTE You may need an additional license to use this feature.
Hot-relocation automatically reacts to I/O failures on redundant
(mirrored or RAID-5) Volume Manager objects and restores redundancy
and access to those objects. The Volume Manager detects I/O failures on
objects and relocates the affected subdisks to disks designated as spare
disks and/or free space within the disk group. Volume Manager then
reconstructs the objects that existed before the failure and makes them
redundant and accessible again. See “Hot-Relocation” for more
information.
NOTE Hot-relocation is only performed for redundant (mirrored or RAID-5)
subdisks on a failed disk. Non-redundant subdisks on a failed disk are
not relocated, but the system administrator is notified of their failure.
Hot-relocation is enabled by default and goes into effect without system
administrator intervention when a failure occurs. The vxrelocd
hot-relocation daemon detects and reacts to Volume Manager events that
signify the following types of failures:
• disk failure—this is normally detected as a result of an I/O failure
from a Volume Manager object. Volume Manager attempts to correct
the error. If the error cannot be corrected, Volume Manager tries to
access configuration information in the private region of the disk. If it
cannot access the private region, it considers the disk failed.
• plex failure—this is normally detected as a result of an uncorrectable