Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

When an SRDF/A single mode session is dropped, the OS automatically starts a cleanup process:

• The primary array marks new incoming writes as being owed to the secondary array.
• The capture and transmit delta sets are discarded, but the data is marked as being owed to the secondary array. All of these owed tracks are sent to the secondary array once SRDF is resumed, as long as the copy direction remains primary to secondary.
• The secondary array marks and discards the receive delta set only. Data is marked as tracks owed to the primary array.
• The secondary array makes sure the apply (N-2) delta set is safely applied to disk; this is the dependent-write consistent image.

When a SRDF/A multiple mode session with Multi-Session Consistency (MSC) is dropped, MSC cleanup operations either:

• Discards any incomplete SRDF/A data, or
• Commits completed data to the R2 to maintain dependent write consistency.

When a SRDF/A multiple mode session with MSC is dropped, additional cleanup is required in fault scenarios where all delta sets of a transition have not been fully applied or discarded.

If a link failure causes protection to be triggered, the daemon may not be able to process all cleanup operations for the R2 devices where the receive and apply delta sets reside. Run the symrdf msc_cleanup command manually from the R2 site. If no consistency group definition is available at the R2 site, direct the cleanup operation to an SRDF (RA) group that was included as part of the consistency group.

Output of the symcfg list command includes flag information for SRDF groups operating in SRDF/A mode. An X in the RDFA Flags "M" column denotes that an MSC cleanup operation is required.

Syntax

Use the msc_cleanup command to cleanup after a session is dropped for devices operating in SRDF/A mode with consistency enabled MSC. The command can be executed by composite group from the R1 or R2 site or by SRDF group from the R2 site.

Use the symcfg list command to check whether a MSC cleanup operation is required.

Use the symcfg list command with the -rdfg all option to display whether a MSC cleanup operation is required for only SRDF (RA) groups on the specified array.

Examples

symrdf -cg mycg msc_cleanup

To cleanup from the remote host at the R2 site for array 123 and direct the command to SRDF group 4:

symrdf -sid 123 -rdfg 4 msc_cleanup