Symptoms

Code: 10.2.0.0 and above only (both arrays) with Solutions Enabler running that supporting code SRDF/A Autonomous Self-Healing SRDF/A Auto-Recovery SRDF/A has dropped but recovered on its own. Unable to remove/move a device from an SRDF/A group while Auto-Recovery is active (as designed) Unable to setup MetroDR while Auto-Recovery is active (as designed) Unable to setup STAR while Auto-Recovery is active (as designed) Unable to enable SRDF Consistency Group while Auto-Recovery is active (as designed)

Cause

The primary reason for an SRDF/A drop is cache usage. With Transmit Idle, SRDF/A can ride out link disruptions. If Spillover is used (for any reason), it is not always able to keep the group from dropping. After a drop, it is required that the customer manually restart. 

Resolution

Engineering has designed a new feature called SRDF/A Auto-Recovery to prevent a customer from having to manually restart SRDF/A if applicable. This feature does not solve a persistent bandwidth limitation. After upgrading to 10.2.0.x or above, the SRDF/A session must be restarted in order for this feature to apply. If it is never restarted after the upgrade, it remains at the legacy format and will not use this feature. After a drop, the code will: Take a recovery snapshot on the R2 side for the devices in the group.Remain in SRDF/A mode: R1 devices become not readyPerforms typical SRDF/A Cleanup (drain spilled cycles, if any, and clear cache writes belonging to cycles) Resume SRDF/A replication resulting in R1->R2 sync.Wait for the sync to complete: If SRDF/A drops again before the sync completes due to user action, restore the recovery snapshot to the R2 and leave SRDF/A mode. The customer is left with a consistent (older) point in time on the R2.If SRDF/A syncs and is consistent, then delete the snapshot on the R2 and continue running in SRDF/AIf SRDF/A drops again due to resource limitations, preserve the recovery snapshot, and retry these steps starting at step 2 above Solutions Enabler or UVP supporting 10.2.0.0 and above: The new group level dynamic parameter "SRDF/A auto recovery" is on by default if both sides are at 10.2.0.0 and aboveChanging the feature to "off" disables the feature for a groupWhen using this feature, SE reports "SRDF/A recovery is active" indicating the group has dropped and is creating a recovery snapshot and recovering consistency

Support Cases