Hitachi VSP G200 System Administration Manual page 76

External parity groups inventory
External parity groups are parity groups in a storage system that is
connected to a storage system that has been onboarded in Storage Advisor.
You can display a list of external parity groups in a storage system that has
been registered with Device Manager - Storage Navigator.
You can access the External Parity Groups page by clicking the External Parity
Groups tile on the detail page for a storage system. If the storage system has
no external parity groups, the tile does not display.
External parity groups are not available for deletion, initialization, or
compression.
If external parity groups have been used to create a pool (outsideStorage
Advisor), you can use their capacity to create volumes in Storage Advisor.
Enabling accelerated compression in Storage Advisor
Accelerated compression can be enabled for parity groups on FMD DC2 drives
that are part of VSP Gx00 models, VSP Fx00 models and VSP G1000, VSP
G1500, or VSP F1500 storage systems. It enable users to realize more virtual
capacity than the actual usable capacity.
Note: Accelerated compression is not compatible with encryption. If a parity
group is encrypted when created, the data cannot be compressed.
Storage Advisor only uses the physical capacity of the FMD DC2 parity groups
for which write is assured.
Accelerated compression can be enabled in the in the Parity Groups inventory
page. The parity groups must be in IN_USE status.
If a pool includes parity groups that have accelerated compression enabled,
you can view the following in the detail page for the pool:
• Expansion Ratio: The ratio of the total capacity of FMD DC2 pool volumes
• Compression Ratio: The ratio of data size compression.
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System Administrator Guide for VSP Gx00 models and VSP Fx00 models
○ IN_USE: Parity group is being used by a storage pool.
○ UNINITIALIZED: The parity group either has no volumes or at least
one of the pool volumes is in Blocked status, or one or more partitions
is uninitialized and has a size greater than 16,787,456 blocks.
○ UNSUPPORTED_ATTACHED: At least one of the pool volumes has a
path to a storage port.
○ UNSUPPORTED_INACCESSIBLE_RESOURCE_GROUP: Parity group
and at least one of its pool volumes are in different resource groups and
user does not have access to one of the resource groups.
with respect to the total capacity of FMD DC2 pool volumes assured for
writing.
Configuring the storage system