HP 4000/6000/8000 HP StorageWorks 4000/6000/8000 Enterprise Virtual Array Conn - Page 7

Logical Volume Manager, Overloaded EVA configurations, High-availability environment recommendations

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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), or vgscan(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

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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)
, or
vgscan(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:
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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