IBM System Storage DS3000 Programming Manual page 119

Notes
Each Enhanced FlashCopy group name must be unique. You can use any combination of alphanumeric
characters, underscore (_), hyphen(-), and pound (#) for the user label. User labels can have a maximum
of 30 characters.
To create an Enhanced FlashCopy group, you must have an associated repository logical drive in which
you store the Enhanced FlashCopy images. You can either use an existing repository logical drive or
create a new repository logical drive. You can create the repository logical drive when you create the
Enhanced FlashCopy group. An Enhanced FlashCopy group repository logical drive is an expandable
logical drive that is structured as a concatenated collection of up to 16 standard logical drive entities.
Initially, an expandable repository logical drive has only a single element. The capacity of the expandable
repository logical drive is exactly that of the single element. You can increase the capacity of an
expandable repository logical drive by attaching additional standard logical drives to it. The composite
expandable repository logical drive capacity then becomes the sum of the capacities of all of the
concatenated standard logical drives.
An Enhanced FlashCopy group has a strict ordering of Enhanced FlashCopy images based on the time
that each Enhanced FlashCopy image is created. An Enhanced FlashCopy image that is created after
another Enhanced FlashCopy image is a successor relative to that other Enhanced FlashCopy image. An
Enhanced FlashCopy image that is created before another Enhanced FlashCopy image is a predecessor
relative to that other one.
An Enhanced FlashCopy group repository logical drive must satisfy a minimum capacity requirement
that is the sum of the following:
v 32 MB to support fixed overhead for the Enhanced FlashCopy group and for copy-on-write processing.
v Capacity for rollback processing, which is 1/5000th of the capacity of the base logical drive.
The minimum capacity is enforcement by the controller firmware and the storage management software.
When a you first create an Enhanced FlashCopy group, it does not contains any Enhanced FlashCopy
images. When you create Enhanced FlashCopy images, you add the Enhanced FlashCopy images to an
Enhanced FlashCopy group. Use the create enhancedFlashCopyImage command to create Enhanced
FlashCopy images and add the Enhanced FlashCopy images to an Enhanced FlashCopy group.
An Enhanced FlashCopy group can have one of these states:
v Optimal - The Enhanced FlashCopy group is operating normally.
v Full - The Enhanced FlashCopy group repository is full. Additional copy-on-write operations can not
be performed. This state is possible only for Enhanced FlashCopy groups that have the Repository Full
policy set to Fail Base Writes. Any Enhanced FlashCopy group in a Full state causes a Needs-Attention
condition to be posted for the storage subsystem.
v Over Threshold - The Enhanced FlashCopy group repository logical drive usage is at or beyond its
alert threshold. Any Enhanced FlashCopy group in this state causes a Needs-Attention condition to be
posted for the storage subsystem.
v Failed - The Enhanced FlashCopy group has encountered a problem that has made all Enhanced
FlashCopy images in the Enhanced FlashCopy group unusable. For example, certain types of
repository logical drive failures can cause a Failed state. To recover from a Failed state use the revive
enhancedFlashCopyGroup command.
Automatic Enhanced FlashCopy Image Deletion
You can configure each Enhanced FlashCopy group to automatically delete Enhanced FlashCopy images
by using the autoDeleteLimit parameter. Automatically deleting the Enhanced FlashCopy images enables
you to avoid having to routinely, manually delete the images that you do not want and that might
Chapter 3. Script Commands
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