VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Moving and Unrelocating Subdisks
242 VERITAS Volume Manager Administrator’s Guide
Examining which subdisks were hot-relocated from a disk
If a subdisk was hot relocated more than once due to multiple disk failures, it can still be
unrelocated back to its original location. For instance, if disk01 failed and a subdisk
named disk01-01 was moved to disk02, and then disk02 experienced disk failure, all
of the subdisks residing on it, including the one which was hot-relocated to it, will be
moved again. When disk02 was replaced, a vxunreloc operation for disk02 will do
nothing to the hot-relocated subdisk disk01-01. However, a replacement of disk01
followed by a vxunreloc operation, moves disk01-01 back to disk01 if vxunreloc
is run immediately after the replacement.
After the disk that experienced the failure is fixed or replaced, vxunreloc can be used to
move all the hot-relocated subdisks back to the disk. When a subdisk is hot-relocated, its
original disk-media name and the offset into the disk, are saved in the configuration
database. When a subdisk is moved back to the original disk or to a new disk using
vxunreloc, the information is erased. The original disk-media name and the original
offset are saved inthe subdisk records. To print allof the subdisks that were hot-relocated
from disk01 in the rootdg disk group, use the following command:
# vxprint -g rootdg -se 'sd_orig_dmname="disk01"'
Restarting vxunreloc After Errors
vxunreloc moves subdisks in three phases:
1. vxunreloc creates as many subdisks on the specified destination disk as there are
subdisks to be unrelocated. The string UNRELOC is placed in the comment field of
each subdisk record.
Creating the subdisk is an all-or-nothing operation. If vxunreloc cannot create all the
subdisks successfully, none are created, and vxunreloc exits.
2. vxunreloc moves the data from each subdisk to the corresponding newly created
subdisk on the destination disk.
3. When all subdisk data moves have been completed successfully, vxunreloc sets the
comment field to the null string for each subdisk on the destination disk whose
comment field is currently set to UNRELOC.
The comment fields of all the subdisks on the destination disk remain marked as
UNRELOC until phase 3 completes. If its execution is interrupted, vxunreloc can
subsequently re-use subdisks that it created on the destination disk during a previous
execution, but it does not use any data that was moved to the destination disk.
If a subdisk data move fails, vxunreloc displays an error message and exits. Determine
the problem that caused the move to fail, and fix it before re-executing vxunreloc.