IBM DS8880 Series, Introduction And Planning Manual

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v IBM Bluemix - Cloud Object Storage
v
OpenStack Swift Based Private Cloud
Dynamic volume expansion
Dynamic volume expansion is the capability to increase volume capacity up to a
maximum size while volumes are online to a host and not in a Copy Services
relationship.
Dynamic volume expansion increases the capacity of open systems and IBM Z
volumes, while the volume remains connected to a host system. This capability
simplifies data growth by providing volume expansion without taking volumes
offline.
Some operating systems do not support a change in volume size. Therefore, a host
action is required to detect the change after the volume capacity is increased.
The following volume sizes are the maximum that are supported for each storage
type.
v Open systems FB volumes: 16 TB
v IBM Z CKD volume types 3390 model 9 and custom: 65520 cylinders
v IBM Z CKD volume type 3390 model 3: 3339 cylinders
v IBM Z CKD volume types 3390 model A: 1,182,006 cylinders
Note: Volumes cannot be in Copy Services relationships (point-in-time copy,
FlashCopy SE, Metro Mirror, Global Mirror, Metro/Global Mirror, and z/OS Global
Mirror) during expansion.
Count key data and fixed block volume deletion prevention
By default, DS8000 attempts to prevent volumes that are online and in use from
being deleted. The DS CLI and DS Storage Manager provides an option to force
the deletion of count key data (CKD) and fixed block (FB) volumes that are in use.
For CKD volumes, in use means that the volumes are participating in a Copy
Services relationship or are in a path group. For FB volumes, in use means that the
volumes are participating in a Copy Services relationship or there is I/O access to
the volume in the last five minutes.
If you specify the -safe option when you delete an FB volume, the system
determines whether the volumes are assigned to non-default volume groups. If the
volumes are assigned to a non-default (user-defined) volume group, the volumes
are not deleted.
If you specify the -force option when you delete a volume, the storage system
deletes volumes regardless of whether the volumes are in use.
Thin provisioning
Thin provisioning defines logical volume sizes that are larger than the physical
capacity installed on the system. The volume allocates capacity on an as-needed
basis as a result of host-write actions.
The thin provisioning feature enables the creation of extent space efficient logical
volumes. Extent space efficient volumes are supported for FB and CKD volumes
Chapter 3. Data management features
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