IBM System Storage DS3000, Programming Manual

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A thin logical drive is dynamic. It has a small initial physical capacity and a large virtual capacity. The
thin logical drive automatically expands to the virtual capacity as data is added to the logical drive.
v
Consistency groups
A consistency group is a container that holds several logical drives so that you can manage all of the
logical drives as a single entity.
To create an Enhanced FlashCopy image, you must first create an Enhanced FlashCopy group and the
associated Enhanced FlashCopy repository logical drive. You can either use an existing repository logical
drive or create a repository logical drive by performing these actions:
v
Identifying the subsystem or disk pool in which you want to place the repository logical drive
v
The capacity for the repository logical drive
You can delete any Enhanced FlashCopy image in an Enhanced FlashCopy group. When an Enhanced
FlashCopy image is deleted, it's definition is removed from the system, and the space occupied by the
Enhanced FlashCopy image in the repository is released and made available for reuse within the
Enhanced FlashCopy group. The Enhanced FlashCopy image can be deleted only in the order of creation,
with the oldest one deleted first.
You can roll back data by either:
v Creating an Enhanced FlashCopy logical drive of an Enhanced FlashCopy image, which enables you to
retrieve deleted files from that Enhanced FlashCopy logical drive (the base logical drive remains
undisturbed).
v
Restoring an Enhanced FlashCopy image to the base logical drive, which enables you to roll back the
base logical drive to a previous state.
Characteristics of Enhanced FlashCopy Images
v
Enhanced FlashCopy images are always created inside Enhanced FlashCopy groups.
v
Each Enhanced FlashCopy image is associated with exactly one Enhanced FlashCopy group.
v
Up to four enhanced FlashCopy groups can be created for a given base logical drive.
v
Up to 32 Enhanced FlashCopy images can be created per Enhanced FlashCopy group.
v
Up to 256 Enhanced FlashCopy logical drives can be created for Enhanced FlashCopy images per
storage subsystem.
About Enhanced FlashCopy Images Premium Feature
See “What's new in this guide” on page xiii for related information.
Enhanced FlashCopy Groups
An Enhanced FlashCopy group is a collection of Enhanced FlashCopy images of a single associated base
logical drive. An Enhanced FlashCopy image is always created within the context of an Enhanced
FlashCopy group, so the identity of the Enhanced FlashCopy group is a key component that must be
specified when creating an Enhanced FlashCopy image.
The purpose of an Enhanced FlashCopy group is to maintain a sequence of Enhanced FlashCopy images
of a given base logical drive without impacting performance. You can set up a schedule for an Enhanced
FlashCopy group to automatically create an Enhanced FlashCopy image at a specific time in the future or
on a regular basis.
Each Enhanced FlashCopy group has a strict ordering of Enhanced FlashCopy images based on the time
an Enhanced FlashCopy image was created. These terms describe the time relationship of Enhanced
FlashCopy images:
v Successor
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IBM System Storage DS3000, DS4000, and DS5000: Command Line Interface and Script Commands Programming Guide