Operation Failed. Fabric is already locked

I ran into this error recently on a Cisco MDS 9000 series switch. It should work on any of the switches in the line, from the MDS 9216 through MDS 9500 series storage switches.

The problem occurs when you are trying to update the device-database. It works fine until you try to device-alias commit, then the error appears. The problem is that someone else was probably trying to update the device-alias database through either the cli or fabric manager. They then exited their session without commiting the change.

To resolve the issue, issue 'show cfs lock' to show the current sessions, then 'clear device-alias session' to remove the offending session.

You should now be able to add your new device-alias and device-alias commit to submit the change.

Enjoy.