HOW TO: Reclaim Cisco UCS Chassis ID?

Today one of our Solution Architects asked me how to reclaim Cisco UCS Chassis ID.

Someone has decommissioned a previous chassis and removed it physically! It was done weeks/months ago and chassis is gone.

If you try to recommission chassis with original ID you’ll get error:
Error: Update failed: [Chassis 3 has already been allocated (N20-C6508 FOX1448GT9G).]

You need to delete old chassis from CLI and then you can use ID again

FI-A# show config all | grep "recommission chassis"
recommission chassis "Cisco Systems Inc" N20-C6508 FOX1326GC2R 4
recommission chassis "Cisco Systems Inc" N20-C6508 FOX1437G8KE 1
recommission chassis "Cisco Systems Inc" N20-C6508 FOX1448GT9G 3 <-- this one was gone
recommission chassis "Cisco Systems Inc" N20-C6508 FOX1452G718 2

If the old chassis# was 3, then do this :

FI-A# delete decommissioned chassis "Cisco Systems Inc" N20-C6508 FOX1448GT9G
FI-A* # commit-buffer

(c) Zbigniew ‘Ziggy’ Misiak