Cautions and restrictions for cache partition – HP XP7 Storage User Manual
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Cautions and restrictions for Cache Partition
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Increased cache memory requirements
Install additional cache memory before partitioning cache. Adding cache memory after CLPRs
have been created is difficult and can be problematic. For details, see
.
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Impact on host performance
Creating and changing cache logical partitions can significantly degrade host performance
and should only be performed during the initial installation and setup of the storage system
or during a maintenance window. If you must perform these changes on a production machine,
use Performance Monitor to verify that the write pending rate and sidefile occupancy rate of
the CLPR and CLPR0 satisfy the following formulas on all MP blades:
◦
For CLPR with decreased cache capacity
Write pending rate x cache capacity before operation /
cache capacity after operation < 30%
Sidefile occupancy rate x cache capacity before operation /
cache capacity after operation < sleep wait threshold x 50%
◦
For CLPR with increased cache capacity
Sidefile occupancy rate < sleep wait threshold x 50%
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Cache partition operations cannot be canceled
Adding or changing CLPR definitions or configurations can take hours to complete. After a
CLPR operation has been started, you cannot cancel or modify the process until the operation
is complete.
•
Minimum cache requirements
You can create a CLPR if the storage system has at least 4 GB cache, except when Cache
Residency is in use. When you create a CLPR while Cache Residency is in use, the remaining
cache size in CLPR0 must be at least 8 GB. The remaining cache size is calculated by
subtracting the Cache Residency cache from the cache size of CLPR0.
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Cache Residency requirement
Cache Residency is a prerequisite for cache partitioning. Cache Residency must be installed
and enabled before you can create cache partitions.
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Using RAID Manager
Do not perform cache partitioning operations from RAID Manager (RAID Manager) and the
GUI at the same time. If you change some settings for Performance Control from RAID Manager,
you cannot change those settings from the GUI. If you do, some settings might not appear.
Before you change features that use Performance Control, delete all Performance Control
settings from the currently used features.
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Interoperability restrictions for cache partitioning
Behaviors
Application
You cannot use Business Copy or Business Copy Z Quick Restore functions that
affect multiple CLPRs.
Business Copy/ Business
Copy Z
You cannot use manual migration when it affects multiple CLPRs.
Auto LUN
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Cache Partition operations