Using external lus as pool-vols, Notes on using xp snapshot, Switching off the power supply – HP StorageWorks XP Remote Web Console Software User Manual
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Using external LUs as pool-VOLs
By using External Storage XP, you can connect multiple arrays to the XP12000/XP10000/SVS200
array. In that case, the original XP12000/XP10000/SVS200 array is called the local array, and the
connected storage arrays are called external arrays. A volume in an external array is called an
external LU. A volume in the local array is called an internal storage virtualizer LDEV (referred to as
an internal LDEV).
If External Storage XP is installed, you can use internal LDEVs and external LUs as pool-VOLs. However,
external LUs are more likely to fail than internal LDEVs. In addition, solutions for external LU failures
are more complicated than those for internal LDEV failures. To minimize the effects of failures, HP
recommends using external LUs as follows:
•
Specify external LUs of only one external array for one pool
•
Do not specify both internal LDEVs and external LUs as pool-VOLs in one pool
You can specify the external LUs of several external arrays for one pool, or use both internal LDEVs
and external LUs as pool-VOLs in one pool, but in that case, remember that problems such as volume
blockade can occur more easily. For example, if a problem occurs and the external LUs being used
as a pool-VOL are blocked, the pool becomes blocked as well. For more information, see
“
For more information about external arrays and solutions for errors related to external LUs, see the
HP StorageWorks External Storage XP user guide.
Notes on using XP Snapshot
This section describes switching off the power supply and replacing the microprogram offline while
XP Snapshot is in use.
Switching off the power supply
Before switching off the power supply while XP Snapshot is running, stop host I/O operations. When
switching on the power supply, XP Snapshot behaves differently depending on whether information
in shared memory remains before and after switching off the power supply.
•
If information in shared memory remains before and after switching off the power supply
You can usually use the pools and XP Snapshot pairs you used before switching off the power.
However, since the array checks the status of pools and pool volumes, if pool volumes are blocked
at that time, the pool is blocked and the status of XP Snapshot pairs changes to PSUE. When this
occurs, you must recover the pools after switching on the power. For more information, see
“
•
If information in shared memory is lost after switching off the power supply
The array has a battery to maintain information in shared memory. However, when a certain time
period elapses after the breaker is turned off, the battery dies and information in shared memory
is lost. If information in shared memory is lost after switching off the power supply, information
about pools and XP Snapshot pairs is erased. Therefore, you must create pools and pairs again
after switching on the power.
For more information about the amount of time before information in shared memory is lost when
the breaker is turned off, contact your HP account support representative.
XP Snapshot User Guide
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