Veritas Volume Manager 5.0 Release Notes HP-UX 11i v3 (5992-1952, August 2011)

Hot-Relocation Issues
The following Hot-Relocation issues are known:
• Problem
Hot-relocation could have an impact on performance.
Workaround
Except for rootvol and swapvol, hot-relocation does not guarantee the same layout of
data or performance after relocation. It is therefore possible that a single subdisk that existed
before relocation may be split into two or more subdisks on separate disks after relocation (if
there is not enough contiguous space on a single disk to accommodate that subdisk).
• Problem
Complete disk information is not included in notification messages.
Workaround
When a disk failure occurs, the hot-relocation feature notifies the system administrator of the
failure and any relocation attempts through electronic mail messages. The messages typically
include information about the device offset and disk access name affected by the failure.
However, if a disk fails completely or a disk is turned off, the disk access name and device
offset information is not included in the mail messages. This is because VxVM no longer has
access to this information.
DMP Issues
Following are the issues related to DMP:
• Problem
DMP threads appear as processes.
Workaround
Unlike the VxVM I/O daemons, DMP daemons, which are also kernel threads, appear in the
output from the ps command as they have an associated process table entry. This difference
in behavior is harmless.
• Problem
Default I/O policy has been modified.
Workaround
The default I/O policy for Active/Active (A/A) arrays has been changed from balanced to
minimumq. The default I/O policy for Asymmetric Active/Active (A/A-A) and Active/Passive
(A/P) arrays has been changed from singleactive to round-robin.
• Problem
Retry period for handling transient errors.
When all paths to a disk fail, there may be certain paths that experience a temporary failure
and can be restored soon. If I/Os are not retried for a period of time, the I/Os may be failed
to the application layer even though some paths are experiencing a transient failure. You can
use the DMP tunable dmp_lun_retry_timeout for more robust handling of such transient
errors. If the tunable is set to a non-zero value, I/Os to a disk with all failed paths will be
retried for the duration specified for the dmp_lun_retry_timeout parameter or until the
I/O succeeds on one of the paths, whichever happens first.
Workaround
You can use the following commands to set and retrieve the tunables:
# vxdmpadm gettune dmp_lun_retry_timeout
28 Veritas Volume Manager 5.0 Release Notes