I have 2 6TB disks in my array currently. One for Data and one for Parity. A few months ago I was starting to get errors on the data disk, so I sent it in to get replaced, leaving ONLY the parity disk in the array. Shoestring budget and highly not ideal, but it was what I had to do.

The RMA process took two months, and in this time, the data drive was being emulated fine, I've been copying/editing files and using my shares as normal from windows.

Fast forward to today, I FINALLY get my replacement drive and go to slot it into the array.

The data rebuild starts, and I keep getting SMART warnings. Then the data rebuild seems to hang at 0.9% and I see no writes happening to the replacement data disk. There are thousands of errors stacking up on the parity drive in the main list as well.

I ran an extended SMART test on my parity drive and I got "Completed: read failure". Did both drives fail? Is it a communication error or something? Diagnostics are attached. I'm hoping someone can help me figure this out. Thank you.

datahub-diagnostics-20260116-1218.zip

11 minutes ago, NickLeylandMedia said:

extended SMART test on my parity drive and I got "Completed: read failure"

Replace.

I know you had already put yourself into a state where you couldn't afford another failure, but that is indeed what you got.

Emulated disk1 is still mounted, but copying from that would still be only reading parity so not really any better than rebuild, except you might be able to see which files you are able to recover.

And since you RMA original disk1 no way to try to recover anything from that either.

Do you have backups? Parity is not a substitute for backups and even more so when you run without really having any redundancy for an extended period.

19 minutes ago, NickLeylandMedia said:

starting to get errors on the data disk

We don't really even know if original disk1 was actually failing, lots of possible interpretations of "errors" with lots of possible causes.

59 minutes ago, trurl said:

We don't really even know if original disk1 was actually failing, lots of possible interpretations of "errors" with lots of possible causes.

In regards to this, the array took the data disk offline itself and began emulating it which was why I RMA'd it. I may have jumped the gun, but I was trying to be safe rather than sorry. Ironically I shot myself in the foot.

The files aren't even being emulated anymore so I think I totally lost the last couple months of data, which luckily is nothing super crucial. I have backups of the rest of my data. Minus some vacation pics but I'll live.

The files were at least being emulated fine and I could view them in the unraid GUI before. Now when I view files I can't see anything. I assume I am now totally hopeless on trying to copy any files off of the emulated disk? The only thing I did was swap the SATA and power cable of the failing parity drive.

You can try running ddrescue on the old parity to clone it to a new disk

53 minutes ago, JorgeB said:

You can try running ddrescue on the old parity to clone it to a new disk

I've used ddrecue in the past to clone disks with success. How can I do this with unraid? Would I have to fire up some kind of VM? or can it be done from the unraid terminal. Apologies if I'm asking this question with wrong terminology, I am still an unraid noob. Thank you!

Edit: when I've done it in the past, all of my drives were hooked up via USB, now they are living in a server.

Edited January 16Jan 16 by NickLeylandMedia

1 hour ago, NickLeylandMedia said:

the array took the data disk offline itself and began emulating it

Bad connections are much more common than bad disks.

Cloning the drive using ddrescue now. Once I do that, do I just assign the newly cloned drive as my new parity drive? Are there other steps to take after that? Or is this just going to be a place for me to go looking for my files?

Edited January 16Jan 16 by NickLeylandMedia

Since you had single parity / single data, the array was a mirror simply due to the way parity is calculated.

You could try mounting the resulting disk as an Unassigned Device.

1 minute ago, trurl said:

You could try mounting the resulting disk as an Unassigned Device.

I will try this once cloning hopefully completes. Thank you for the help.