Logical Volume Manager
Before creating snapshots or snapclones of a device managed by Logical Volume Manager (LVM), be
sure to verify the LVM configuration. After creating a snapshot or snapclone of a physical volume, run
vgchgid(1M) to break the association between the volume group and the snapshot or snapclone.
Otherwise, snapshots or snapclones appear to LVM as an alternate path to the original physical volume.
This causes data corruption if the snapshot or snapclone is added later to the volume group using
vgextent(1M),vgimport(1M),orvgscan(1M).
When a path to a device managed by LVM becomes unavailable because of a controller failure, path
link failure, switch failure, or HBA failure, I/O requests can be delayed for up to one minute, affecting
the responsiveness of mirrored logical volumes.
When a physical volume becomes unavailable, applications experience a delay while an I/O request
to that volume times out. By default, this delay is 30 seconds, but you can change the time-out value
using the pvchange(1M) command.
Overloaded EVA configurations
Persistent EVA overload may indicate an overloaded configuration, and additional resources are
required to handle the workload. Consult your HP account or service representative for help to properly
configure the EVA for your newly designed or existing configuration.
High-availability environment recommendations
If you have a high-availability environment, your system may experience I/O time-out conditions under
heavy I/O loads. If I/O time-outs occur, HP recommends that you use the pvchange command to
increase the IO_timeout value from the default of 30 seconds to no more than 60 seconds. The
increased IO_timeout value allows for longer I/O completion times and for logical unit number
(LUN) access delays if a controller failover occurs.
NOTE:
Ensure that you have HP ServiceGuard configured properly. More information is available on the
ServiceGuard web site: http://docs.hp.com/hpux/ha/index.html#ServiceGuard.
gsssu utility
Use the following command to access SSSU:
# gsssu
In the command text box, enter an SSSU command. For example:
select manager ip_address username=username password=password
4000/6000/8000 Enterprise Virtual Array connectivity 5.1A for HP-UX release notes 7
