Cautions for changing the MP unit

• Changes to the MP unit ID for an external volume should be made during off-peak hours when the I/O load is as low as possible. Do not change the MP unit ID when the I/O load is high -- for example: during initial copy of ShadowImage, TrueCopy, global-active device, or Universal Replicator.
• After you change the MP unit ID for an external volume, wait more than 30 minutes before you try to change the MP unit ID again for the same external volume.
• When you change the MP unit ID for an external volume, you should use Performance Monitor before and after the change to check the load status.
• Before and after changes are made, it is recommended that the cache write-pending rate (%) for all CLPRs is lower than 50%.
• Do not change the MP unit IDs for several external volumes during a short period of time. As a guideline, you can change 10% or less of the total number or the full workload of external volumes to which the same MP unit ID is assigned at the same time.