IBM DS8000 manual LSS13

Servers

LSS11

1st

Completed

LSS12

2nd

Wait

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.

3rd

dependency for each write operation

LSS13

Wait

This write operation is not completed because 2nd write operation is not completed.

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.

Chapter 7. Copy Services 135