Cache Pool - Cache unmountable: no file system


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Hello,

 

Wondering if anyone can help me with an issue I am having with my Cache pool. Basically after a reboot today, when I started up the array I saw the following:

84426140_CacheDrives.thumb.png.ba0f09b5d6be410d1d997a95bdde5c94.png

 

Along side this I see the below asking me if I want to format the primary cache drive. Now obviously I do not want to as I don't want to loose data.

Format.thumb.png.09f85fed9ad155a722913226cc26a5d2.png

 

I then ran a btrfs check --readonly /dev/sdb1 which came with the following output:

Opening filesystem to check...
Checking filesystem on /dev/sdb1
UUID: ab81d341-8531-4c08-8fa1-645911b301fd
cache and super generation don't match, space cache will be invalidated
found 310226411520 bytes used, error(s) found
total csum bytes: 0
total tree bytes: 90783744
total fs tree bytes: 29900800
total extent tree bytes: 60588032
btree space waste bytes: 16964433
file data blocks allocated: 156191051776
 referenced 154714845184

I then did a btrfs check --repair /dev/sdb1 which showed the following:

Starting repair.
Opening filesystem to check...
Checking filesystem on /dev/sdb1
UUID: ab81d341-8531-4c08-8fa1-645911b301fd
[1/7] checking root items
Fixed 0 roots.
[2/7] checking extents
incorrect offsets 12845 12358
incorrect offsets 12845 12358
incorrect offsets 12845 12358
incorrect offsets 12845 12358
Shifting item nr 94 by 487 bytes in block 1254219743232
Shifting item nr 95 by 487 bytes in block 1254219743232
Shifting item nr 96 by 487 bytes in block 1254219743232
Shifting item nr 97 by 487 bytes in block 1254219743232
Shifting item nr 98 by 487 bytes in block 1254219743232
Shifting item nr 99 by 487 bytes in block 1254219743232
items overlap, can't fix
check/main.c:4336: fix_item_offset: BUG_ON `ret` triggered, value -5
btrfs[0x42f27d]
btrfs[0x43842d]
btrfs[0x438960]
btrfs[0x43950c]
btrfs[0x43d495]
btrfs(main+0x90)[0x40ecc0]
/lib64/libc.so.6(__libc_start_main+0xeb)[0x1473a7ed6e5b]
btrfs(_start+0x2a)[0x40ef4a]
Aborted

So at this point I am stumped on what to do to resolve the issue.

 

I have been able to set the primary cache as no device and then start the array at which point it seems the secondary cache drive is working fine and has all the data I need. However preferably I do not want to run at a reduced redundancy for an extended period of time.

 

If I am infact being stupid and do need to format the primary cache drive to then make it re-sync the raid I can do that. Any help infact would be very much apprriciated.

 

Appologies this post is VERY long, I just wanted to make sure that I covered all the options I could find before asking for help.

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7 hours ago, trurl said:

Okay great that information helped.

 

As I had the secondary cache working and all the data was there I just copied it from the single drive cache pool to the array. I then stopped the array, assigned the primary cache back and started the array. I then ticked the format box and started the format of the primary cache.

 

As expected this formatted the cache pool, so all I had to do is restore the files to the cache and everything was back to normal.

 

Just so I know for future, reading the errors shown can someone explain what happened?

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