Last week a received an email saying that my second disk had failed so I went and replaced it, I received another email this morning saying "disk failure detected" and another message saying if the disk failed basically replace it straight away, when I got home it was disk 2 again (the new one). I pulled it out and put it back in, it didn't seem to do anything apart from take the NAS offline, I couldn't do anything to see it so I had no option but kill the power to the NAS to see it again, while it was off I switched the drives in the bays around, once it powered on again the system says everything is ok.
I checked the SMART information for both drives and the new one has "raw read error rate" 23, the second drive doesn't show any errors.
Disks are 1 x WD Red 2TB & new WD Red 4TB, see attached file for screenshots of the SMART information, I am now not convinced the second drive failed at all.
I also just noticed on the status page it says the disks are: X-RAID2 (Not-Redundant), I searched this and found a page saying pull the first drive and see if you can still access your files, I did this and the NAS went offline again, I restarted it (by killing the power again as it was unresponsive) and RAIDar now says corrupt root.
This was my storage device with backups and my iTunes library now I can't even access it.
The log indicated the sync finshed around 6 hours later, I received the second email about 5 days after I installed the new disk in bay 2, when I checked the NAS it indicated the new drive had failed, I shut in down and swapped the drives around, the new drive in bay 1 and the older drive in 2 and it restarted ok and everything seemed to be ok execpt when I came across the message saying it was non redundant.
I searched that and someone suggested pulling 1 drive out while it was up to see if you could still access the data, off memory I pulled out the new drive in bay 1 and it became un responsive, I ended up killing the power and that's when RAIDr said its currupt.
I think its time for a new NAS, it there any way of getting the data off these drives without the NAS?
I notice that the 4TB HDD has a Current Pending Sector. That is an indicator that the HDD is going bad or its bad already.
I think that's an over-statement with only 1 current pending sector. It is a concern that should be watched, but a single bad sector (whether pending or reallocated) does't mean the disk is bad.
The format of the raw read error rate is vendor specific, and without a WDC decoder ring it's hard to tell if its a concern or not. Unfortunately I've never seen a description of what the raw values mean. Similarly for seek error rate.
That said, we can't rule out a drive issue, and certainly something went wrong.
As far as remedial actions you took - you should have powered down before removing disk 1, and then tried rebooting. My guess is that the corrupt root resulted from pulling the plug, but of course if the system isn't responding you'd have had no other option.
Contacting support is the best option. There are some off-line tools that might be able to access the data (r-linux for windows being a free one you could try).
