Server hangs after RAID-6 single disk failure

[Martin42]

We have HPE servers with P420i v8.32, P840 v7.00 and P440ar v7.00 and Ubuntu Linux. Each of these have RAID 6 arrays with 6-8 SSDs. On three occasions, the following has happened: A single disk in this RAID has failed, and after a little while, like 30 mins, the servers hangs. When we restart the server, the server starts up in degraded mode and works well.

What is the reason for the server hanging? It becomes inaccessible over SSH, and all systems on it stops. Is this a feature of the RAID-controller, or is it the file system in Ubuntu Linux that stops the disk? Or is it the disk driver? Have anyone else had this problem?

[shiva_jr]

Hi @Martin42,
At first, the hang may be due to something else. RAID 6 has minimum redundancy of two drives. For one disk failure, the RAID won't trouble, it tries to rebuild. 

Did you replace the failed disk?
Is the RAID working fine now?
I believe, now you experience no hang status. If not-
a. Check the RAID controller logs
b. Check dmesg and syslog
c. If SSH console of the OS is not working. Please check the OS is booting or not, the network and ssh service so that you can get the root cause from OS perspective.

Regards,
Shiva_JR

[Martin42]

@shiva_jr Thank you for the answear! How can I check the RAID controller logs? It works fine after a reboot, but does require a reboot to start again after a disk failure.