Chapter 8. Administration - Configure
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Draft Document for Review August 30, 2007 12:59 am
7065Admin_Configure.fm
Dynamic Capacity Expansion (DCE), to increase an array's capacity using unconfigured
capacity (in the form of unused drives)
Dynamic Logical Drive Expansion (DVE), to increase a logical drive capacity using free
capacity available on the array of the standard or FlashCopy repository logical drive
Failed VolumeCopy
A VolumeCopy can fail because of a read error from the source logical drive, a write error to
the target logical drive, or because of a failure on the storage system that affects the source
logical drive or target logical drive. A critical event is logged in the event log when the
VolumeCopy fails, and a Needs-Attention icon is displayed in the Enterprise Management
Window. While a VolumeCopy has this status, the host has read-only access to the source
logical drive, and read and write requests to the target logical drive will not take place until the
failure is corrected by using the Recovery Guru.
Preferred controller ownership
During a VolumeCopy, the same controller must own both the source logical drive and target
logical drive. If both logical drives do not have the same preferred controller when the
VolumeCopy starts, the ownership of the target logical drive is automatically transferred to the
preferred controller of the source logical drive. When the VolumeCopy is completed or is
stopped, ownership of the target logical drive is restored to its preferred controller. If
ownership of the source logical drive is changed during the VolumeCopy, ownership of the
target logical drive is also changed.
Failed controller
Controller ownership must be manually changed to the alternate controller to allow the
VolumeCopy to complete under the following conditions: If a VolumeCopy has a status of In
Progress, and its preferred controller fails, the ownership transfer does not occur
automatically in the failover.
Restrictions
The following restrictions apply to the source logical drive, target logical drive, and the storage
system:
The source logical drive is available for read I/O activity only while a VolumeCopy has a
status of In Progress or Pending. Write requests are allowed after the VolumeCopy is
completed.
A logical drive can be used as a target logical drive in only one VolumeCopy at a time.
The maximum allowable number of logical drive copies per storage system is dependent
upon the number of target logical drives available on your storage system.
A storage system can have up to eight VolumeCopies running at any given time.
The target logical drive capacity must be equal to or greater than the source logical drive
capacity.
A source logical drive can be a standard logical drive, FlashCopy logical drive, FlashCopy
base logical drive, or a Remote Mirror primary logical drive.
A target logical drive can be a standard logical drive, a base logical drive of a disabled or
failed FlashCopy logical drive, or a Remote Mirror primary logical drive.
Tip: In practice, VolumeCopy must only be used with FlashCopy, in order to shorten
source logical driver read-only period of time.
