Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide

The Array Witness method requires two Witness SRDF groups:

• One between the R1 array and the witness array
• One between the R2 array and the witness array

Some characteristics of Witness SRDF groups are:

• There can be only one Witness SRDF group between any two arrays.
• Witness SRDF groups must be empty. SRDF/Metro prevents the creation of SRDF device pairs in Witness SRDF groups.
• The SRDF group must be created as a Witness SRDF group; there is no mechanism to switch an SRDF group between Witness and non-Witness.
• When choosing to use a witness to protect the SRDF/Metro configuration, the witness selects the winner side in the event of a failure.

This section shows how to create, modify, and remove Witness SRDF groups.

Witness SRDF group attributes

Some attributes of Witness SRDF groups are different from those of a standard SRDF group. Differences include:

• Link limbo - The default value for an Witness SRDF group is 1 second. Dell EMC recommends not to increase this value, as this decreases Witness protection.