VERITAS Volume Manager 3.1 Administrator's Guide

Volume Manager Operations
Hot-Relocation
Chapter 3108
unrelocate operation will fail and none of the subdisks will be moved.
When the vxunreloc program moves the hot-relocated subdisks, it
moves them to the original offsets. However, if there some subdisks
existed which occupied part or all of the area on the destination disk, the
vxunreloc utility will fail. If failure occurs, you have two choices: (1)
move the existing subdisks somewhere else, and then re-run the
vxunreloc utility, or (2) use the -f option provided by the vxunreloc
program to move the subdisks to the destination disk, but allow the
vxunreloc utility to find the space on the disk. As long as the
destination disk is large enough so that the region of the disk for storing
subdisks can accommodate all subdisks, all the hot-relocated subdisks
will be “unrelocated” without using the original offsets.
A subdisk that was hot-relocated more than once due to multiple disk
failures will still be able to 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 the
subdisks residing on it, including the one which was hot-relocated to it,
will be moved again. When disk02 is replaced, an unrelocate operation
for disk02 will not do anything to the hot-relocated subdisk disk01-01.
However, a replacement of disk01 followed by the unrelocate operation
moves disk01-01 back to disk01 when the vxunreloc program is run,
immediately after the replacement.
Restarting the vxunreloc Utility After Errors
Internally, the vxunreloc program moves the subdisks in three
phases.The first phase is creates as many subdisks on the specified
destination disk as there are the number of the subdisks to be
unrelocated. When the subdisks are made, the vxunreloc program fills
in the comment field in the subdisk record with the string UNRELOC as an
identification. The second phase is the actual data moving. If all the
subdisk moves are successful, the third phase proceeds to clean up the
comment field of the subdisk records.
Making the subdisk is a all-or-none operation. If the vxunreloc program
cannot make all the subdisks successfully, no subdisk is made and the
vxunreloc program exits. The operation of the subdisks move is not
all-or-none. One subdisk move is independent of another, and as a result,
if one subdisk move fails, the vxunreloc utility prints an error message
and then exits. But, all of the subsequent subdisks remain on the disk
where they were hot-relocated and will not be moved back. For subdisks
that made their way back home, the comment field in their subdisk