Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

On both sides of an SRDF configuration, the array keeps an account of the tracks that are "owed" to the other side. Invalid tracks are tracks that are not synchronized between the two devices in an SRDF pair. Remote invalids are tracks owed to the remote member of the device pair.

For example:

• The logical connection between an R1 device and its R2 is suspended.
• If both devices are made write-accessible, hosts on both sides of the SRDF links write to their respective devices, without the writes being mirrored.
• This creates invalid tracks on the R1 side, and remote invalid tracks on the R2 side.
• Each invalid track represents a track of data that has changed since the two sides were split. To re-establish the logical links between the R1 and R2, the invalid tracks must first be resolved.

How you resolve invalid tracks depends on which control operation you perform. For example if you have remote invalids on both the R1 and R2 sides:

• An establish operation copies the modified R1 tracks to the R2 side.

  Any tracks that were modified on the R2 side are overwritten with data from corresponding tracks on the R1 side.

• A restore operation copies the modified R2 tracks to the R1 side.

  Any tracks that were modified on the R1 side are overwritten with data from corresponding tracks on the R2 side.