A 2,5TB Disk of my array with 3TB parity had read errors, so I replaced it with a 4TB Disk. I thought I could use 3TB of this 4TB disk because of the smaller parity drive, but unRaid told me to do a swap-disable. After a bit of reading in the forums I did as told. unRaid copied the parity drive to the new disk, rebuilt the 2,5TB drive on the former parity disk and expanded the array.

 

Then I started the parity check. Every now and then I looked at the progressing parity check via webgui and everything looked fine. But now at nearly 90% complete, I looked again and I have thousands of sync errors, starting in sector 5860533064 and then all eight sectors. Is that because I didn't preclear the parity disk, so that the part of the disk > 3TB is not initialized? Should I do a second parity check with correcting parity and everything is back to normal?

 

Thanks for your help!

syslog.txt

A 2,5TB Disk of my array with 3TB parity had read errors, so I replaced it with a 4TB Disk. I thought I could use 3TB of this 4TB disk because of the smaller parity drive, but unRaid told me to do a swap-disable. After a bit of reading in the forums I did as told. unRaid copied the parity drive to the new disk, rebuilt the 2,5TB drive on the former parity disk and expanded the array.

 

Then I started the parity check. Every now and then I looked at the progressing parity check via webgui and everything looked fine. But now at nearly 90% complete, I looked again and I have thousands of sync errors, starting in sector 5860533064 and then all eight sectors. Is that because I didn't preclear the parity disk, so that the part of the disk > 3TB is not initialized? Should I do a second parity check with correcting parity and everything is back to normal?

 

Thanks for your help!

 

No, it's not because you didn't pre-clear the parity disk ... parity does not need to be cleared (and for that matter, neither do data disks => Pre-Clear is an excellent utility that not only eliminates the need for UnRAID to clear a new disk, but also gives the new disk a thorough scrub and Q/C check ... but it is NEVER "required".

 

I gather you did a non-correcting check; so Yes, you need to do a correcting check now ... and THEN do another check after that to confirm everything's okay.    Hopefully the rebuild worked okay with the Parity Swap process.  Personally, I'd never replace parity without having a known-good array -- I'd have replaced your 2.5TB drive with a 3TB drive so it could be rebuilt without issue; then done a parity check to confirm all was perfect (i.e. 0 sync errors);  and THEN replaced the parity drive.    But it's a bit late to do that 

This is why parity-swap-disabled procedure exists. Did you do a parity check before changing disks?

This is why parity-swap-disabled procedure exists. Did you do a parity check before changing disks?

 

There's a good reason you should do monthly parity checks ==> so you always KNOW that you have good parity in case of a drive failure.    Unfortunately, you can NOT do a "parity check before changing disks" when the problem is you've had a failed disk ... as was the case here:

 

A 2,5TB Disk of my array with 3TB parity had read errors, so I replaced it with a 4TB Disk.

 

 

I did a parity check, that's why I stumbled upon the read erros on the 2,5TB-Drive. There were no sync errors reported, but 66 read errors on the mentioned drive. So I decided to exchange the drive.

At this point there's really nothing you can do except a correcting parity check.

 

I would then run a comparison of the data on the "new" (former parity) data drive with your backups to confirm that all's okay.

 

Then I'll bite the bullet now and do the correcting parity check.

 

That's a good idea to compare the data with the backups. I'm doing the backups with SyncBack SE. I remember an option for bit-wise comparison.

 

Thanks for your advice!

 

*starting parity check*

That's a good idea to compare the data with the backups. I'm doing the backups with SyncBack SE. I remember an option for bit-wise comparison.

 

SyncBack lets you do a bit-wise check after it's written a backup; but I don't believe it's got an option to do JUST a comparison between two folders.    I use FolderMatch for that .. but it's not free [although you can download it use it free for a trial period (I think 30 days):  http://www.foldermatch.com/index.htm

... it will also synchronize directories, but I prefer SyncBack SE for that.  I only use FolderMatch for my comparisons.

 

There are a few free folder comparison utilities, but I haven't looked at them in a long time, as I simply use FolderMatch.