LUN-replication on Unity works slightly different than it previously did on VNX or even Clariion. In these older generations, when you deleted the mirrorview Mirror Group, both the primary and secondary LUNs became usable as separate entities.

In Unity the secondary LUN is a different beast. First of all: in Unity you can only set up replication from the primary Unity/LUN. The process on the source-Unity will create a LUN-replica and a replication session on both Unitys.

But what happens when you need hosts to access the secondary LUN? A failover works as designed and the previous secondary LUN becomes writable, but when you break the replication session, the replica-LUN has a flag that needs to be reset, but you’ll need the CLI to do that. This is how I did it:

• In Unisphere I listed all LUNs and I made sure to include the “CLI ID” column
• I noticed the ID of the LUN I need to grant access to is “res_56”
• I started PUTTY and made sure logging to a file was configured so I could easily browse / search the possibly large amount of data some commands can produce, especially “-detail” commands tend to be very explicit
• Log in as the “service” user to the Unity command line

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