HELP: BTRFS Cache Unmountable: Invalid pool config


Go to solution Solved by JorgeB,

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Hey Guys, 

 

I need some help. Did a clean shut down of my Unraid server yesterday to install some new ram. Installed the ram, booted normally and went to start the array and my cache pool would not start. 

 

Current configuration is a 3 SSD's in a BTRFS Raid5 Pool. (I know, Raid5 is experimental with BTRFS and not the best idea.) but Its been running fine for the last couple of years and I'm not sure what would have caused this error. 

Most of the files are backed up on my HDD array, so worst case scenario I can format and rebuild. But I'd rather fix it if possible. 

 

Last week I did a scrub and a rebalance of the cache pool and both completed just fine. 

Usage ratio was at about ~95%

Windows reported just over a 1tb of space free on the pool. 

Unraid Version: 6.10.2

 

So far I have tried a few things from this Guide, but some direction/help would be greatly appreciated. 

 

Feel free to ask any questions you might have, or let me know what logs/data I need to provide. 

 

Thanks!

 

 

 

 

 

 

Screen Shot 2022-06-22 at 9.30.46 PM.png

Screen Shot 2022-06-23 at 11.23.00 AM.png

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Don't try fixing the filesystem, that's not the problem, pool should be OK, problem is parity is registering as an invalid btrfs filesyetem during device scan:

 

Jun 23 10:35:47 Cold1 emhttpd: shcmd (236): /sbin/btrfs device scan
Jun 23 10:35:48 Cold1 root: ERROR: cannot scan /dev/sdi1: Input/output error

 

This is why the pool doesn't mount, this is a known issue but usually only happens when there's a single btrfs array device, though, and because of how parity it works, it can happen when there's an even number of btrfs array devices, you have 5.

 

Any recent changes to the array, like did you add a new disk?

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I have not added any devices to the Cache pool, But I did add 5 new platter drives to the HDD Array last week.. They got formatted as btrfs (because it was set to auto) but I attempted to change them to XFS as that's what the rest of the HDD in the array are running. 

 

 

Screen Shot 2022-06-23 at 12.18.14 PM.png

Edited by Trex Arms
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Ok, I will try that.

 

With the cache drives unmountable, those devices show up at the bottom next to the "format all unmountable disks" Do I need to Physically remove them from the system so they aren't present, format the HDD's and then add the Caches drives back in?

Edited by Trex Arms
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  • Solution
Just now, Trex Arms said:

Do I need to Physically remove them from the system so they rant present

You just need to unassign them all, them when the disks are re-formatted xfs (or btrsf encrypted) just re-assign all the pool devices and start the array, it will import the existing pool.

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7 minutes ago, JorgeB said:

You just need to unassign them all, them when the disks are re-formatted xfs (or btrsf encrypted) just re-assign all the pool devices and start the array, it will import the existing pool.

Trying that Now. I'm guessing its okay to do this?  Not seeing the format drive option unless I start the array. 

Screen Shot 2022-06-23 at 12.38.47 PM.png

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