Scrub showing tons of errors

[Sergio]

Hello

I have snapraid for my media library with 4 drives (3x3tb and 1x6 tb as parity). I had 2x3TB drives for data and 1x3TB as parity. I recently added the 6TB parity drive so I did a full sync and everything went well. After a while, I decided to remove my original parity drive to use it for data since I was running out of space. I did the process of removing the info from the snapraid.conf file, deleted parity files and content, re-synced everything again and it was a success.

Yesterday I ran a scrub (12%) and it threw thousands of errors like these:

parity_error:8127578:parity: Data error, diff bits 1041545/2097152
parity_error:8127579:parity: Data error, diff bits 1047987/2097152
parity_error:8127580:parity: Data error, diff bits 1045859/2097152
parity_error:8127581:parity: Data error, diff bits 1045588/2097152
parity_error:8127582:parity: Data error, diff bits 1047491/2097152
parity_error:8127583:parity: Data error, diff bits 1048251/2097152
parity_error:8127584:parity: Data error, diff bits 1049974/2097152
parity_error:8127585:parity: Data error, diff bits 1049261/2097152
parity_error:8127586:parity: Data error, diff bits 1049584/2097152
parity_error:8127587:parity: Data error, diff bits 1049126/2097152
parity_error:8127588:parity: Data error, diff bits 1048891/2097152
parity_error:8127589:parity: Data error, diff bits 1047840/2097152
parity_error:8127590:parity: Data error, diff bits 1049643/2097152
parity_error:8127591:parity: Data error, diff bits 1049689/2097152
parity_error:8127592:parity: Data error, diff bits 1049389/2097152

I decided to

• Do a long SMART test of all the drives and everything came out well. No problem with any of the drives.
• Do a snapraid check -a command and everything came out well too.
• Did a diff test and the results show that no files were modified since the last scrub.
• I did a snapraid check -v -S 8126270-B 1367949 -l log.txt to check for all the blocks that came out "wrong" and it gave me a nice 90MB log with errors like the ones that I'm showing at the top. However, I also get a huge list of files saying something like this (Obviously for different files)

status:correct:Archivos2:Plex/Series/Batman- The Animated Series/Season 1/Batman The Animated Series - 1x04 - Feat of Clay (1) - 480p.mp4

I decided to play some of my video files and they all look good, no problem with video or audio. Right now I'm doing a full check just to see what happens.

My question here is, what could be going wrong? Files seem good to me, and before I modified the array I never had any problems with any scrub tests.

Thanks for your help.

[Leifi Plomeros]

My best guess is that you did this:

1. Add 2-parity on 6 TB disk
2. Remove first parity from 3 TB disk
3. Tell snapraid that first parity is inside the 2-parity file on the 6 TB disk

The content of parity and 2-parity are completely different.

Correct way to do what you want would have been this:

1. Get rid of 2-parity from 6 TB disk
2. Remove 2-parity from config
3. Sync
4. Copy parity file from 3 TB disk to 6 TB disk
5. Update config that first parity is now on 6 TB disk.

Edit: Best way to resolve the situation is:

1. Copy the 2-parity file from 6 TB to 3 TB
2. Delete parity from 6 TB
3. Update config and tell snapraid that 2-parity is on 3 TB disk and first parity is on 6 TB disk.
4. Let snapraid fix the missing first parity on 6 TB disk
5. Remove the second parity in config
6. Sync

[Sergio]

Yes, you're right. I thought both files were the same.

I don't have the parity file from the first 3TB drive anymore, but if I'm getting you right, I should get what it's technically my 1st parity (now in my 6TB drive) copied back into my 3TB drive, then let snapraid rebuild the parity on the 6TB drive.

Would forcing a full sync of the parity on 6TB drive fix the problem too? Essentially starting from scratch.

Thanks for your super quick reply.

Edit: 2nd parity back to 3TB, tell snapraid that 1st parity is in 6TB (it won't), and then rebuild 1st parity in 6TB drive. Remove 3TB drive from config.