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Data Recovery from Multiple Drive Failure

Featured Replies

Hello All,

 

I have a server running Unraid v6.8.3 that I fear I may have bricked. The server has one parity disk and six data disks. About a month ago disk #2 failed. I successfully replaced it with a larger Seagate 4tb and all was well. In doing so, I noticed that disk #5 had many errors (if memory serves is was 1900ish) and I figured it was on the way out. To be proactive, I ordered another Seagate 4tb and replaced that drive. During the rebuild, drive #2 became unreadable or in an error state. 

 

I thought that I could put the old Western Digital drive back into slot #5 (it never failed completely) and be good to go. Not the case. 

 

While I was able to muddle through building this system about a decade ago, I am by no means tech savvy or competent in this operating system. I am really hoping someone here can point me towards a few things to try to recover some of the data on the server!

 

Currently the array is stopped (and cannot be started) with two drives in an error state (disk #2 and disk #5). I can select the old drives from the drop down but if I do so I get blue squares next to them and it still will not let me start the array. My thinking is this; both of those drives should contain all of their original data that was present prior to the system going berserk. The parity drive is probably confused. Is it possible to rewrite the parity drive with the two old disks installed? I have spare new drives and spare slots in the tower. 

 

Please help and thank you in advance!

 

Frank

  • Community Expert

Please post the diagnostics.

 

16 minutes ago, frank12589 said:

In doing so, I noticed that disk #5 had many errors (if memory serves is was 1900ish) and I figured it was on the way out.

Note that if these errors happened during the rebuild, likely there will be some corruption on the rebuilt disk.

 

 

  • Author

Understood, about the errors. What would the procedure look like to bring back the array? Unassign the parity? I know I have already made a few mistakes and I don't want to dig my hole any deeper. Any input would be greatly appreciated!

  • Community Expert
3 hours ago, JorgeB said:

Please post the diagnostics.

Would like to look at these first.

  • Author

Sure thing, please see attached. Unfortunately I never thought of this and have rebooted several times since the issue. I thought the system should be powered down to change drives. 

Unconfirmed 820993.crdownload

  • Community Expert

Disl2 looks healthy, there are a lot of UDMA CRC errors so you should replace the SATA cable, disk5 appears to be failing, you can try force enabling disk2 to replace disk5, but note that this will only work if parity is still valid:

 

-Tools -> New Config -> Retain current configuration: All -> Apply
-Check all assignments and assign any missing disk(s) if needed, including the new disk5, replacement disk should be same size or larger than the old one
-IMPORTANT - Check both "parity is already valid" and "maintenance mode" and start the array (note that the GUI will still show that data on parity disk(s) will be overwritten, this is normal as it doesn't account for the checkbox, but it won't be as long as it's checked)
-Stop array
-Unassign disk5
-Start array (in normal mode now) and post new diags

  • Community Expert

Emulated disk5 is mounting, if contents look correct you can rebuild.

  • Author

OK, I stopped the array, assigned a new disk #5 and started the array. It is in the rebuild phase. 

 

There are currently 4.5 Million errors on disk #2. I attached a log. Think the errors can be stemming from a bad cable? I don't have any spares to try, but I did just order a bunch that will be here Thursday.

 

Thank you

Unconfirmed 304274.crdownload

  • Community Expert
47 minutes ago, frank12589 said:

Think the errors can be stemming from a bad cable?

It does like like a power/connection issue, and I did say:

4 hours ago, JorgeB said:

Disl2 looks healthy, there are a lot of UDMA CRC errors so you should replace the SATA cable

 

Recommend canceling and trying again with a new cable.

 

 

  • Author

Excellent. I really appreciate your help. I shut 'er down. I will replace the cables when they arrive on Thursday, start it back up with the data rebuild and observe for errors. Fingers crossed. Can't thank you enough. Have a nice night.

 

Frank

  • Author

OK, new SATA cables installed and the rebuild is complete. There were still errors but not nearly as many (336 compared to over 100 million a few minutes into the last attempt). See attached. I think it's smooth sailing now. I was ready to trash this thing a week ago. The support on this forum is incredible. Thanks again!

 

Frank

Unconfirmed 24415.crdownload

  • Community Expert

T

7 minutes ago, frank12589 said:

There were still errors but not nearly as many (336

Those are logged as a disk issue with parity, you should run an extended test, also note that if the errors coincided with data on the rebuilt disk, it could result in some corruption on the affected file(s), but should be minimal.

  • Community Expert

Looks like you attached a diagnostics download that wasn't finished yet. I was able to open it with 7zip but didn't examine it to see what might be missing.

 

You should pay more attention to what you attach.

  • Author

That's odd, I just ran it again and the file size is actually smaller (84.3kb). The first file is the same size as the one I uploaded (84.5kb). Sorry if I didn't do it correctly. 

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