IBM System Storage DS3000, Programming Manual

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An Enhanced FlashCopy image that is created after another Enhanced FlashCopy image has been
created, also called newest.
v Predecessor
An Enhanced FlashCopy image that is created before another Enhanced FlashCopy image, also called
oldest.
The terms newest and oldest are arguments used in the CLI commands.
An Enhanced FlashCopy group uses an Enhanced FlashCopy group repository logical drive to save all
data for the Enhanced FlashCopy images contained in the group. An Enhanced FlashCopy image
operation uses less disk space than a full physical copy because the data stored in the Enhanced
FlashCopy logical drive repository logical drive is only the data that has changed since the Enhanced
FlashCopy image has been taken.
An Enhanced FlashCopy group is created initially with one Enhanced FlashCopy group repository logical
drive, with a default capacity of 40% the capacity of the base logical drive. The Enhanced FlashCopy
group repository logical drive initially contains a small amount of data, which increases with subsequent
data updates. If needed, you can increase the size of the Enhanced FlashCopy logical drive repository
logical drive by combining unused repository logical drives to the Enhanced FlashCopy group repository
logical drive or by creating additional Enhanced FlashCopy group repository logical drives.
The only types of logical drives that can contain an Enhanced FlashCopy group are these:
v Standard logical drives
v
Thin logical drives
Non standard logical drives, such as Enhanced FlashCopy logical drives, cannot be used for Enhanced
FlashCopy groups. The base logical drive can reside on either an subsystem or a disk pool.
Note: Enhanced FlashCopy logical drives and Enhanced FlashCopy groups cannot coexist on the same
base logical drive.
Characteristics of Enhanced FlashCopy Groups :
v
Enhanced FlashCopy groups can be initially created with or without Enhanced FlashCopy images.
v Depending on your configuration, a single associated base logical drive has a maximum limit of
Enhanced FlashCopy groups.
v
Depending on your configuration, an Enhanced FlashCopy group has a maximum limit of Enhanced
FlashCopy images.
v
Each Enhanced FlashCopy image is associated with exactly one Enhanced FlashCopy group.
Repository Logical drives
Every Enhanced FlashCopy image is created in the context of exactly one Enhanced FlashCopy group. An
Enhanced FlashCopy group is a sequence of Enhanced FlashCopy images of a single associated base
logical drive. A given Enhanced FlashCopy group has exactly one Enhanced FlashCopy logical drive
repository logical drive that is used to save data for all of the Enhanced FlashCopy images that are part
of the Enhanced FlashCopy group. When a new Enhanced FlashCopy image is created in an Enhanced
FlashCopy group, all previously-created Enhanced FlashCopy images in that Enhanced FlashCopy group
become static and stop consuming additional repository space. The newly-created Enhanced FlashCopy
image begins consuming repository space during processing of ensuing copy-on-write actions for the
associated base logical drive.
The Enhanced FlashCopy group repository logical drive is a standard logical drive that can be expanded
to accommodate an increasing number of Enhanced FlashCopy images. The Enhanced FlashCopy group
repository logical drive is structured as a concatenated collection of up to 16 standard logical drives.
Chapter 6. Using the Enhanced FlashCopy Images Premium Feature
6-3