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* btrfs ontop of LVM ontop of MD RAID1 supported?
@ 2024-03-02 15:01 Nigel Kukard
  2024-03-02 15:47 ` Roman Mamedov
  0 siblings, 1 reply; 6+ messages in thread
From: Nigel Kukard @ 2024-03-02 15:01 UTC (permalink / raw)
  To: linux-btrfs


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Hi there,

I hope everyone is doing great today!

I'm wondering if btrfs ontop of LVM ontop of MD RAID1 is supported?  
I've managed to reproduce with 100% accuracy severe data corruption 
using this configuration on 6.6.19.

2 x 1.92T NVMe's in MD RAID1 configuration
LVM volume created ontop of the MD RAID1
btrfs filesystem on the LV

I then write about 100-200G of data. Create a snapshot. Read/write the 
file and get these messages...

Mar 02 11:34:01 xxxx kernel: BTRFS error (device dm-1): bdev 
/dev/mapper/lvm--raid-images errs: wr 0, rd 0, flush 0, corrupt 43, gen 0
Mar 02 11:34:01 xxxx kernel: BTRFS warning (device dm-1): csum failed 
root 5 ino 274 off 12477722624 csum 0xea911494 expected csum 0xc29349a8 
mirror 1
Mar 02 11:34:01 xxxx kernel: BTRFS error (device dm-1): bdev 
/dev/mapper/lvm--raid-images errs: wr 0, rd 0, flush 0, corrupt 44, gen 0

It seems to be more related to larger files, a bunch of smaller files I 
have didn't see any corruption until a few hours later. Snapshots and 
subvolumes don't seem to affect the results in a noticeable way.

I've managed to reproduce it on 4 completely different systems as I 
first thought it may be a hardware issue, but its consistent across 
completely different enterprise platforms, however they all have 
enterprise NVMe disks, but are different brands.

Using ext4 and comparing data after each set of writes is consistent. 
Its just btrfs that seems to be having an issue.

When running a scrub, I get these messages...

Mar 02 11:39:38 xxxx kernel: BTRFS info (device dm-1): scrub: started on 
devid 1
Mar 02 11:39:39 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 4036689920 on dev 
/dev/mapper/lvm--raid-images physical 5118820352
Mar 02 11:39:39 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 4295163904 on dev 
/dev/mapper/lvm--raid-images physical 5377294336
Mar 02 11:39:39 xxxx kernel: BTRFS warning (device dm-1): checksum error 
at logical 4295163904 on dev /dev/mapper/lvm--raid-images, physical 
5377294336, root 263, inode>
Mar 02 11:39:39 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 4307615744 on dev 
/dev/mapper/lvm--raid-images physical 5389746176
Mar 02 11:39:39 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 4511760384 on dev 
/dev/mapper/lvm--raid-images physical 5593890816
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 8687386624 on dev 
/dev/mapper/lvm--raid-images physical 9769517056
Mar 02 11:39:40 xxxx kernel: BTRFS warning (device dm-1): checksum error 
at logical 8687386624 on dev /dev/mapper/lvm--raid-images, physical 
9769517056, root 267, inode>
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 8689352704 on dev 
/dev/mapper/lvm--raid-images physical 9771483136
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 8690335744 on dev 
/dev/mapper/lvm--raid-images physical 9772466176
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 8691974144 on dev 
/dev/mapper/lvm--raid-images physical 9774104576
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 8692236288 on dev 
/dev/mapper/lvm--raid-images physical 9774366720
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): unable to fixup 
(regular) error at logical 8692957184 on dev 
/dev/mapper/lvm--raid-images physical 9775087616
Mar 02 11:39:40 xxxx kernel: BTRFS error (device dm-1): fixed up error 
at logical 8723496960 on dev /dev/mapper/lvm--raid-images physical 
9805627392

It gets progressively much worse over time the more writes that happen. 
Starting at around 800 or so errors most uncorrectable escalating into 
the thousands.

I'm using default mount options for btrfs and Arch Linux.

(please kindly CC me as I'm not subscribed to the mailing list)

Kind regards
-N


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^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2024-03-19 13:26 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-03-02 15:01 btrfs ontop of LVM ontop of MD RAID1 supported? Nigel Kukard
2024-03-02 15:47 ` Roman Mamedov
2024-03-02 16:09   ` Nigel Kukard
2024-03-02 16:19   ` Roman Mamedov
2024-03-19 11:05   ` Nigel Kukard
2024-03-19 13:26     ` Nigel Kukard

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