Several months ago we had a power outage. Despite being on a UPS so it should have been protected from an outage or a spike, the DNS reported that a drive had failed. I don't honestly remember capturing exactly what it said so I don't remember if it gave specifics of which drive had failed.
I shutdown the unit until I figured out if I had a power issue. When I brought it back up the Status->Device Info page said in the Hard Drive Info section - 2 hard drives, vol_1, raid 1. Degraded.
After a restart, the logs says HDD1 drive failed.
At the bottom, it gave the name of the drives but doesn't use the HDD1 / HDD2 labels and doesn't flag one as failed in any way.
Right S/N ending 7857
Left S/N ending 6912
On the Tools->Raid page, it said volume degraded and gave the info for the 7857 drive. It had the radio buttons for enable auto-rebuild and the manual rebuild button.
So, which is the dead or at least out of synch drive?
On the Tools->Raid page, because it named the 7857 drive, I interpreted that to mean that it was the functioning, current drive and it was running degraded. So the 6912 drive may or may not be healthy but it is the one out of synch. Not taking any chances, I replaced that drive.
Now the Status->Device Info Hard Drive Info is different
It was:
Right S/N ending 7857
Left S/N ending 6912 (this was in the bay on the right, facing the unit but interpreting HDD1/2 as left to right, this seems to make sense as the drive to replace)
Now it is:
Right S/N ending 8185 (new drive, placed in the bay on the right, facing the unit)
Left S/N ending 7857 (right became left !!?)
Now at startup, the logs say HDD2 failed. So going with my HDD1 = Left and HDD2 = Right but has nothing to do with physical position in the unit, this makes sense. The 7857 is the primary drive and the new drive is "second" drive and failed because it is not in synch.
I guess I'm not surprised when ROM based hardware config utilities are a bit crude, but the PDF users manual doesn't do any better at being clear about what is going on.
I'm waiting for the resynch to finish to see what I have. If they both contain data that is no older than a few months ago, then I have my answer. So this post boils down to the question: Can I reinstall the drive I pulled out and resynch again? How do I know which way the synch will go, i.e. which will be the source and which will be the target of the resynch? I can isolate and reformat to blank the drive I want to be the target but I want to be sure the rebuild will do what I want.
I'm also beginning to get the suspicion that I didn't need to replace the drive. The hard disk did not physically fail, it just fell out of synch. If I had just hit the manual rebuild button, it might have resynched and that would have been the end of it. But how could I know that! The UI and the docs don't mention anything like that. Argh!!!!
I'm expecting to hear at least one response say reformat both drives and restore from backup. Always an option but I would really like to understand how it is supposed to work...
Thanks.
Is the Tools->Raid drive named the one that is OK but running degraded because it doesn't have it's mirror?
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Topic: RAID 1 Rebuild - UI not clear about what needs fixing (Read 2623 times)