Here is pretty common problem in UCS 2.0 release.
At any stage of UCS upgrade  one or more blades go into discovery mode and never finishes it. Depending on the version they can get stuck at any percentage but usually between 4% and 40%.
Most of the time a corruption occurs in SEEPROM of  M81kr CNA card because of this corruption checksum fails and UCS cannot recognize the mezzanine card any longer and this prevent Discovery from finishing.
You can see the following errors when this happens:
Configuration Error: adaptor-inoperable. Discovery State: Insufficiently Equipped.
Adapter 1 in server 1/1 has unidentified FRU 

There are multiple Cisco bugs for this issue CSCub16754, CSCty34034, CSCub48862, CSCub99354 and I’ve seen it happening on 2.0(1q), 2.0(2r), 2.0(3a) releases.
Unfortunately the issue is not fixed and there is no workaround. The good thing is that if this occurs the fix is pretty simple and quick and no hardware replacement is needed but only Cisco TAC can fix this or whoever has access to their internal resources.

To verify if corruption occurred you can do the following:

1. SSH to UCSM IP
2. Enter connect cimc x/y (Chassis/Blade)
3. Enter mezz1fru on the versions starting from 2.0(3a) you need to enter fru
   If corruption has occurred the last line of the output will show something like
   ‘Checksum Failed For: Board Area!’

The other method to check is to look at the logs. (more…)