Chapter 8. Administration - Configure 185
Draft Document for Review August 30, 2007 12:59 am 7065Admin_Configure.fm
controller experiences a reset, the copy request is restored and the copy process resumes
from the last known progress boundary.
After submitting a copy request, the source logical drive is only available for read I/O activity
while a logical drive copy has a status of In Progress, Pending, or Failed. Write requests are
allowed after the logical drive copy is completed. Read and write requests to the target logical
drive will not take place while the logical drive copy has a status of In Progress, Pending, or
Failed.
These restrictions are necessary to ensure the integrity of the point-in-time copy. If the logical
drive being copied is large, this can result in an extended period of time when a production
application cannot make updates or changes to the data.
As shown in Figure 8-68, FlashCopy, which allows a point-in-time copy to be made while
maintaining read/write access, enables a complete copy to be created without interrupting the
I/O activity of the production logical drive.
Figure 8-68 VolumeCopy integrated with FlashCopy
8.5.2 Copying data for greater access
Some of the advantages of VolumeCopy are:
Migration
As storage requirements for a logical drive change, the VolumeCopy function can be used to
copy data to a logical drive in an array that utilizes larger capacity disk drives within the same
Important: Because all write requests to the source logical drive are rejected when the
VolumeCopy is taking place, it is essential to minimize the time it takes to complete the
copy operation. This is why VolumeCopy must always be used in conjunction with
FlashCopy. In other words, first make a FlashCopy of the source logical drive, then perform
a VolumeCopy of the FlashCopy (see Figure 8-68).
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