HP StorageWorks XP Remote Web Console Software - Manual (Page 6)

•
In manual migrations, the system administrator specifies the volumes to be migrated and the
migration destinations, and then executes migrations.
•
In auto migrations, XP Auto LUN automatically determines the volumes to be migrated and
the migration destinations, and also executes migrations automatically.
CAUTION: When an error condition exists in the storage system, resource usage can increase
or become unbalanced. Do not use data collected during an error condition as the basis for
planning XP Auto LUN operations.
NOTE:
•
Manual migration supports external volumes, but auto migration does not. Even when you
use a manual migration, you cannot examine the estimated usage rate after migration because
the usage rates of external volumes cannot be collected. For details on external volumes, see
the HP StorageWorks XP24000/XP20000 Performance Monitor User Guide.
•
Manual migration supports HP StorageWorks XP Thin Provisioning Software virtual volumes,
but auto migration does not. If source volumes for manual migration are XP Thin Provisioning
virtual volumes, the target volumes can be internal volumes, external volumes, or XP Thin
Provisioning virtual volumes.
•
XP Auto LUN operations are completely nondisruptive—the data being migrated can remain
online to all hosts for read and write I/O operations throughout the entire volume migration
process.
•
Consider that storage system-tuning operations can improve performance in one area while
at the same time decreasing performance in another. Suppose that parity groups A and B
have average usage values of 20% and 90%, respectively. XP Auto LUN estimates that if one
volume is migrated from parity group B to parity group A, the usage values will become 55%
and 55%. If you perform this migration operation, the I/O response time for parity group B
will probably decrease, and the I/O response time for parity group A may increase, while
the overall throughput may increase or decrease.
•
XP Auto LUN should be performed only when you can expect a large improvement in storage
system performance. XP Auto LUN may not provide significant improvement for cases in which
parity group or volume usage varies only slightly, or for cases in which overall DKP or DRR
usage is relatively high.
•
From an open-system host, users can also use RAID Manager to perform manual volume
migration by using commands. To perform volume migration by RAID Manager, XP Auto LUN
should be installed on the storage system. For details on manual volume migration by using
RAID Manager, see
“Using RAID Manager for Manual Volume Migration” (page 66) . For
details on RAID Manager, see the HP StorageWorks XP RAID Manager User Guide.
6 Overview of HP StorageWorks XP Auto LUN Software