It seems system was in hung state . The message > Feb 21 22:26:23 <server> kernel: INFO: task perl:20596 blocked for more than 120 seconds. Just indicates that process 20596 was stuck/hang in cpu for more than 120 seconds. To begin with the troubleshooting, I would suggest you to check what this process does. Whether this required any REMOTE storage/disk access. Btw, the same perl process is going to D state/hang state first/always ? If no remote storage/disk access is required for this perl application AND In case you are running this application as root user, try run this application as a normal user in which a resource limitation is applicable via limits.conf. If the process required a storage/NFS access, you may want to check the disk/storage status at the time when application moved to D state. I understand that you can't predict the issue time and perform all the checks mentioned above. afaik, to find the root cause of this problem, you may want to analyse core dump collected at the time of the issue. Cheers, Dominic