I have being running on three 2TB hard drives in software raid for a little under a year how under Ubuntu Server.
After restarting my computer mdadm would not allow a boot because the raid was degraded.
I booted in to Ubuntu desktop USB trail mode thingy. After looking in disk until I managed to see that 2 drives were fine but one of them had seemed to have lost its partition tables. The smart report on it said it was perfect with nothing to report.
I have added it back to the raid array which is going to take some time. But was wondering what made this happen? Can I stop it happening again? Should I replace that drive anyway or test it somehow?