Administrator Guide

default is 75 percent. If the pool is not overcommitted, the event has an Informational severity. If the pool is overcommitted,
the event has a Warning severity.
● High Threshold: When this percentage of virtual pool capacity has been used, event 462 is generated to alert the
administrator to add capacity to the pool. This value is automatically calculated based on the available capacity of the
pool minus 200 GB of reserved space. If the pool is not overcommitted, the event has an Informational severity. If the pool
is overcommitted, the event has Warning severity and the system uses write-through cache mode until virtual pool usage
drops back below this threshold.
● Enable overcommitment of pools?: This check box controls whether the allocated size of the volumes can exceed the
physical capacity of the pool.
NOTE: The above pool settings apply only to virtual pools.
○ When the overcommit feature is disabled, the host does not lose read or write access to the pool volumes when the pool
reaches or exceeds the high threshold value.
○ When the overcommit feature is enabled, the storage system sends the data protect sense key Add, Sense: Space
allocation failed write protect to the host when the pool reaches or exceeds the high threshold value. If the
host is rebooted after the pool reaches or exceeds the high threshold value, the host loses read and write access to the
pool volumes. The only way to regain read and write access to the pool volumes is to add more storage to the pool.
To check if the pool is overcommitted, hover the cursor over the pool in the pools table to display the Pool Information panel .
If the Pool Overcommitted value is True, the pool is overcommitted. If the Pool Overcommitted value is False, the pool is not
overcommitted. If you try to disable overcommitment and the total space that is allocated to thin-provisioned volumes exceeds
the physical capacity of their pool, an error states that there is insufficient free disk space to complete the operation and
overcommitment remains enabled.
NOTE: If your system has a replication set, the pool might be unexpectedly overcommitted because of the size of the
internal snapshots of the replication set. If the pool is overcommitted and has exceeded its high threshold, its health shows
as degraded in the Pools topic. If the pool is overcommitted and has exceeded its high threshold, its health shows as
degraded in the Pools topic.
Verifying and scrubbing disk groups
Verify a disk group
If you suspect that a fault-tolerant, mirror or parity, disk group has a problem, run the Verify utility to check the disk group's
integrity. For example, if you haven't checked the system for parity inconsistencies recently and are concerned about the disk
health, verify its disk groups. The Verify utility analyzes the selected disk group to find and fix inconsistencies between its
redundancy data and its user data. This utility fixes parity mismatches for RAID 3, 5, 6, and 50, and finds but not fixes mirror
mismatches for RAID 1 and 10. This task can be performed only on a disk group whose status is fault tolerant and online (FTOL).
It cannot be performed for NRAID or RAID 0 read cache disk groups.
Verification can last over an hour, depending on the size of the disk group, the utility priority, and the amount of I/O activity.
You can use a disk group while it is being verified. When verification is complete, event 21 is logged and specifies the number
of inconsistencies found. Such inconsistencies can indicate that a disk in the disk group is going bad. For information about
identifying a failing disk, use the SMART option. For more information, see Configuring SMART.
If too many utilities are running for verification to start, either wait until those utilities have completed and try again, or abort
a utility to free system resources. If you abort verification, you cannot resume it. You must start the process again from the
beginning.
Verify a disk group
1. In the Pools topic, select the pool for the disk group that you plan to verify in the pools table.
NOTE:
To see more information about a pool, hover the cursor over the pool in the table. See Viewing pools for more
details about the Pool Information panel that appears.
2. Select the disk group in the Related Disk Groups table.
3. Select Action > Disk Group Utilities.
The Disk Group Utilities panel opens, showing the current job status.
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Working in the Pools topic