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Chapter 7. Copy Services 135
Figure 7-14 Consistency Group: Example 2
In all cases, if each write operation is dependent, Consistency Group can keep the data
consistent in the backup copy.
If each write operation is not dependent, the I/O sequence is not kept in the copy that is
created by the Consistency Group operation. See Figure 7-15 on page 136. In this case, the
three write operations are independent. If the volumes in LSS12 are in an extended long busy
state and the other volumes in LSS11 and 13 are not, the 1st and 3rd operations are
completed and the 2nd operation is not completed.
1st
2nd
3rd
dependency
for each write
operation
Servers
Completed
Wait
Wait
LSS11
LSS12
LSS13
This write operation is
not completed
because 2
nd
write
operation is not
completed.
This write operation is
completed because
LSS11 is not in an
extended long busy
condition.
This write operation is
not completed
because LSS12 is in
an extended long
busy condition.