paulmorabi

Apologies for the late reply. I've been ordering NIC's and cables to test. Yes, you're correct it was a bad cable. All good now.

Thanks. I don't have another disk handy so I am going to try moving the 4TB disk to a separate pool as this is the lone disk assigned to the downloads share. I've started backing up its contents to another share on the array. I will remove the disk from the current array (following these instructions) and then add it to its own pool. I understand this will format the data on the disk so I'll need to delete and recreate the downloads share on the new pool and then copy the stuff back over? Is that correct?
 
EDIT: Above operation seems to have worked reducing the overall server load.
 
 

Crashes stopped after this and I replaced the RAM so seems like it was a faulty RAM stick.