HP XP P9500 Storage - Manual (Page 139)

6. In the Confirm window, confirm the settings, in Task Name type a unique name for this task
or accept the default, and then click Apply.
If Go to tasks window for status is checked, the Tasks window opens.
About releasing pages in a THP V-VOL
Releasing pages in a THP V-VOL frees up pool capacity. When a page in the THP V-VOL contains
zero data. The pool free capacity increases after the pages are released. You can perform the
reclaiming zero pages operation to each V-VOL. You can confirm progress of the processing by
Remote Web Console. For details, see
(page 327) . You can stop the performing of the reclaiming
zero pages. If you stop the performing of the reclaiming of zero pages, the already reclaimed
zero pages cannot be restored.
Logically, there is no difference between a page with just zero data and the area of a THP V-VOL
without a page allotted. They are effectively identical. However, the former uses pool capacity
and the latter does not.
Zero pages can be relaimed when all the following conditions are satisfied:
•
The THP V-VOL is not used in conjunction with another P9500 product that does not support
reclaiming zero pages.
See “Using Thin Provisioning or Smart Tiers with other P9500 products” (page 75) .
•
LDEV formatting is not being performed on the THP V-VOL.
•
The THP V-VOL is not blocked.
•
The THP V-VOL is associated with a pool.
•
The pool associated with the THP V-VOL is not blocked, or is full and blocked.
•
The THP V-VOL is not TSE-VOL.
Pages that include control cylinders are not processed when releasing pages in a THP V-VOL.
While releasing pages from a THP V-VOL, performance of the host I/O to the THP V-VOL may
temporarily decrease due to scanning for non-zero data.
If you stop an operation to reclaim zero pages in mid-stream, the pages that have been released
will remain as free pool capacity.
After an operation to reclaim zero pages, Thin Provisioning automatically balances usage levels
among pool-VOLs in the pool. This rebalancing is performed on all of the THP V-VOLs and pool-VOLs
in the pool. If you do not want automatic balancing of the usage levels of pool-VOLs, call the HP
Technical Support to change your configuration.
Thin Provisioning does not automatically balance the usage levels among pool-VOLs if the cache
memory is not redundant or if the pool usage reaches up to the threshold.
If all the data written to a page assigned to a THP V-VOL is binary zeroes, you can reclaim the
page and return it to the pool's available capacity.
If you have started an operation to reclaim zero pages, and the storage system loses power, the
shared memory is disrupted. The operation does not automatically continue after the storage system
restarts.
In the following cases, an operation reclaim zero pages stops and THP V-VOL pages are not
released.
•
LDEV formatting is performed while the operation to reclaim zero pages is in progress.
•
The pool-VOL accessed by the target THP V-VOL is blocked.
•
The pool associated with the target THP V-VOL is blocked while the operation to reclaim zero
pages is in progress.
•
Cache memory failure occurs the operation to reclaim zero pages is in progress.
Managing pools and THP V-VOLs 139