How to Unmask a Disk that is Masked by CMC Migration

During the various phases of a CMC migration process, the source and/or destination disk is masked to prevent accidental usage by the user. Further, any snapshot taken by the destination storage (when a CMC Integration is invoked) is also masked unless there is an additional Action defined to unmake the destination prior to calling the snapshot (and in that case, yet another Action should be defined following the Snapshot action to mask the destination again). All these necessitates the availability of a mask/unmask function. This function is indeed available as part of the mTDI command line tool.

For Windows, the following example masks or unmasks Disk 4 (as enumerated by Computer Management's Disk Management tool):

"\Program Files\CirrusData\mtdi\mtdi.exe" descramble \\.\PHYSICALDRIVE4

For Linux, the following example masks or unmasks /dev/sdj:

mtdi descramble /dev/sdj

The same command is used to mask or unmask the disk because the algorithm is an XOR operation and is therefore a toggle. Only the first 4 KB of the disk is scrambled. The rest of the disk is untouched. If you accidentally run the above command on a disk that is not intentional, simply run it again to undo the action.

Updated on: 11/07/2022

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