HP XP Racks - Manual (Page 6)

is repeated until all differential data on the source volume is copied. The following figure illustrates
the data flow during a migration operation.
Figure 1 Data flow during an Auto LUN operation
There is an upper limit to the number of times a copy operation is executed, and the limit depends
on the capacity of the source volume. The limit increases as the capacity of the source volume
increases. When differential data still exists after copy operations are repeated to the upper limit,
the migration fails. Before attempting the migration again, the workload between the host and the
storage system should be adequately reduced, preferably to a value below 50 IOPS (input/output
operations per second).
Once the volumes are fully synchronized (that is, there is no differential data on the source volume),
the XP7 storage system completes the migration by swapping the Reserve attribute (from target
volume to source volume) and redirecting host access to the target volume. The status of the target
volume becomes normal. Auto LUN performs all migration operations synchronously (that is, one
migration at a time). The following figure illustrates the state of the volumes after a migration
operation.
Figure 2 Data flow after an Auto LUN operation
Immediately after the source volume and target volume are swapped (that is, the migration is
complete), the RAID level before the migration might be displayed, or an internal error might occur
in the storage system. If this occurs, try to resolve the issue by updating the display of the window.
6 Overview of Auto LUN