Data Replication Manager HSG80 ACS Version 8.6-4P Release Notes

Common Platform Issues
Release Notes – Data Replication Manager HSG80 ACS Version 8.6-4P 11
Controller Saturation
High usage of many remote copy set and non-remote copy set LUNs will have a
serious impact on the performance of the remote copy set LUNs, causing controller
saturation and possibly starving a full copy operation.
A saturated controller condition begins approximately when idle time falls to 25% or
less. When this occurs, you may see Aborted Command errors through the Command
Line Interface (CLI).
To prevent controller saturation:
• Avoid placing multiple heavy use loads on the controllers.
• Use the VTDPY screen to monitor controller idle time percentage. Adjust load
accordingly to maintain an idle time of 25% or greater.
RAID 5 Remote Copy Set Target Drop
RAID 5 remote copy set targets may be dropped under the following combined
conditions:
• No write history log disk is configured, and
• Host I/O is accessing the initiator remote copy set LUNs.
When both target controllers are shut down, a full copy operation will be triggered.
When the target controllers are restarted, they will begin a 3-minute memory
diagnostic.
While the memory diagnostics are running, the full copy I/O to RAID 5 target LUNs
will be stalled. Therefore, after approximately 2 minutes, a timeout will occur and the
target LUNs will be dropped from the remote copy set. This target drop problem
occurs only on RAID 5 remote copy set LUNs.
Remedies:
• To prevent target LUN drop, before target controllers are booted or powered on,
set port_2_topology on both initiator controllers to offline. Wait 5 minutes after
target controllers are restarted to allow for memory diagnostics to complete before
setting port_2_topology on the initiator controllers back to fabric.
• If the target LUNs are dropped, wait 5 minutes to allow for the target controller
memory diagnostics to complete, then add the targets back into the remote copy
sets. The full copy operation will begin.