Extent Space Efficient (Ese) Capacity Controls For Thin Provisioning - IBM DS8882F Introduction And Planning Manual

and are supported for all Copy Services functionality, including FlashCopy targets
where they provide a space efficient FlashCopy capability.
Releasing space on CKD volumes that use thin provisioning
Extent Space Efficient (ESE) capacity controls for thin
provisioning
Use of thin provisioning can affect the amount of storage capacity that you choose
to order. ESE capacity controls allow you to allocate storage appropriately.
With the mixture of thin-provisioned (ESE) and fully-provisioned (non-ESE)
volumes in an extent pool, a method is needed to dedicate some of the extent-pool
storage capacity for ESE user data usage, as well as limit the ESE user data usage
within the extent pool. Another thing that is needed is the ability to detect when
the available storage space within the extent pool for ESE volumes is running out
of space.
ESE capacity controls provide extent pool attributes to limit the maximum extent
pool storage available for ESE user data usage, and to guarantee a proportion of
the extent pool storage to be available for ESE user data usage.
An SNMP trap that is associated with the ESE capacity controls notifies you when
the ESE extent usage in the pool exceeds an ESE extent threshold set by you. You
are also notified when the extent pool is out of storage available for ESE user data
usage.
ESE capacity controls include the following attributes:
ESE Extent Threshold
ESE Extent Status
Note: When the size of the extent pool remains fixed or is only increased, the
allocatable physical capacity remains greater than or equal to the allocated physical
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DS8882F Introduction and Planning Guide
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On an IBM Z host, the DFSMSdss SPACEREL utility can release space
from thin provisioned CKD volumes that are used by either Global Copy
or Global Mirror.
For Global Copy, space is released on the primary and secondary copies. If
the secondary copy is the primary copy of another Global Copy
relationship, space is also released on secondary copies of that relationship.
For Global Mirror, space is released on the primary copy after a new
consistency group is formed. Space is released on the secondary copy after
the next consistency group is formed and a FlashCopy commit is
performed. If the secondary copy is the primary copy of another Global
Mirror relationship, space is also released on secondary copies of that
relationship.
The percentage that is compared to the actual percentage of storage
capacity available for ESE customer extent allocation when determining the
extent pool ESE extent status.
One of the three following values:
v 0: the percent of the available ESE capacity is greater than the ESE extent
threshold
v 1: the percent of the available ESE capacity is greater than zero but less
than or equal to the ESE extent threshold
v 10: the percent of the available ESE capacity is zero