If you get this error:

CRITICAL: megacli:[Volumes(2): DISK0.0:Degraded,DISK1.1:Degraded: Devices(4): 06,07,04=Online 05 (WD-WCC1P1090364WDC WD2000FYYZ-01UL1B1 01.01K02)=Unconfigured(bad)]

You need to rebuild the drive. First use smartctl to check if the disk is ok.

Then check which disk is bad with

megacli -pdlist -a0

If the disk for example is this one

...
Enclosure Device ID: 252 
Slot Number: 0
...

get full info

megacli -pdinfo -physdrv[252:0] -a0

Steps:

1. Change the state to good

megacli -pdmakegood -physdrv "[252:0]" -a0
Adapter: 0: EnclId-252 SlotId-0 state changed to Unconfigured-Good.
Exit Code: 0x00

2. If the following commands shows “Foreign flag” in “Foreign state” you need to clear it with:

megacli -cfgforeign -clear -a0
Foreign configuration 0 is cleared on controller 0.

3. Designate the drive as hotspare

megacli -pdhsp -set -physdrv "[252:0]" -a0
Adapter: 0: Set Physical Drive at EnclId-252 SlotId-0 as Hot Spare Success.

4. The automatic rebuild should now start. Check with

megacli -pdinfo -physdrv[252:0] -a0

... Firmware state: Rebuild ...

megacli -pdrbld -showprog -physdrv "[252:0]" -a0
Rebuild Progress on Device at Enclosure 252, Slot 0 Completed 1% in 3 Minutes.

Exit Code: 0x00

Or start the rebuild manually with

megacli -pdrbld –start –physdrv “[252:0]” –a0

• megacli commands
• output megacli predictive error
• megacli replace disk

• https://supportforums.cisco.com/t5/security-documents/recovering-a-disk-shown-as-unconfigured-bad-in-raid/ta-p/3116431