[linux-lvm] lvcreate hangs forever during snapshot creation when suspending volume
Thomas Deutschmann
whissi at whissi.de
Tue Aug 2 03:01:57 UTC 2022
Hi,
Zdenek Kabelac wrote:
> Now - you suggests you are able to reproduce this issue also on your bare
> metal hw - in this case run these 3 commands before 'lvcreate'
Here we go:
> $ dmsetup table
> devDataStore1-volMachines: 0 5368709120 linear 9:127 2048
> devDataStore2-volData: 0 11596414976 linear 259:6 2048
> devSystem-volRoot: 0 419430400 linear 8:3 50333696
> devSystem-volSwap: 0 50331648 linear 8:3 2048
> $ dmsetup info -c
> Name Maj Min Stat Open Targ Event UUID
> devDataStore1-volMachines 253 1 L--w 1 1 0
LVM-AzPWjYw7Nts8ZnQyaKdjJ8cyaG0b9umSFIx2fo4zZvW8QplyYM3jNaQSFXSDMNDW
> devDataStore2-volData 253 0 L--w 1 1 0
LVM-RZtslsKN16YTBhJZE4qzFkvFQVChUKEcyUS1BwtKv3CeDUnKkTz53p8IwT5pqMnk
> devSystem-volRoot 253 3 L--w 1 1 0
LVM-TZlj0Mwy3bA5QpPVVpeO6ncufQ2Va36MgxgnvVn7fNGMme2prgc1xn9e25vua36d
> devSystem-volSwap 253 2 L--w 2 1 0
LVM-TZlj0Mwy3bA5QpPVVpeO6ncufQ2Va36Mp6kfZF6l8ubeUOo00BrK7kFGK8JvcG6X
> $ dmsetup ls --tree
> devDataStore1-volMachines (253:1)
> L- (9:127)
> devDataStore2-volData (253:0)
> L- (259:6)
> devSystem-volRoot (253:3)
> L- (8:3)
> devSystem-volSwap (253:2)
> L- (8:3)
...and during lvcreate when the system hangs:
> $ dmsetup table
> devDataStore1-volMachines: 0 5368709120 linear 9:127 2048
> devDataStore1-volMachines-real:
> devDataStore1-volMachines_snap:
> devDataStore1-volMachines_snap-cow: 0 209715200 linear 9:127 5368711168
> devDataStore2-volData: 0 11596414976 linear 259:6 2048
> devSystem-volRoot: 0 419430400 linear 8:3 50333696
> devSystem-volSwap: 0 50331648 linear 8:3 2048
> $ dmsetup info -c
> Name Maj Min Stat Open Targ Event UUID
> devDataStore1-volMachines 253 1 LI-w 1 1 0
LVM-AzPWjYw7Nts8ZnQyaKdjJ8cyaG0b9umSFIx2fo4zZvW8QplyYM3jNaQSFXSDMNDW
> devDataStore1-volMachines-real 253 4 -I-w 2 0 0
LVM-AzPWjYw7Nts8ZnQyaKdjJ8cyaG0b9umSFIx2fo4zZvW8QplyYM3jNaQSFXSDMNDW-real
> devDataStore1-volMachines_snap 253 6 -I-w 0 0 0
LVM-AzPWjYw7Nts8ZnQyaKdjJ8cyaG0b9umSHue1IrGu69toKQ0ZdcbSv97i3xq5YP2v
> devDataStore1-volMachines_snap-cow 253 5 L--w 1 1 0
LVM-AzPWjYw7Nts8ZnQyaKdjJ8cyaG0b9umSHue1IrGu69toKQ0ZdcbSv97i3xq5YP2v-cow
> devDataStore2-volData 253 0 L--w 1 1 0
LVM-RZtslsKN16YTBhJZE4qzFkvFQVChUKEcyUS1BwtKv3CeDUnKkTz53p8IwT5pqMnk
> devSystem-volRoot 253 3 L--w 1 1 0
LVM-TZlj0Mwy3bA5QpPVVpeO6ncufQ2Va36MgxgnvVn7fNGMme2prgc1xn9e25vua36d
> devSystem-volSwap 253 2 L--w 2 1 0
LVM-TZlj0Mwy3bA5QpPVVpeO6ncufQ2Va36Mp6kfZF6l8ubeUOo00BrK7kFGK8JvcG6X
> $ dmsetup ls --tree
> devDataStore1-volMachines (253:1)
> L- (9:127)
> devDataStore1-volMachines-real (253:4)
> devDataStore1-volMachines_snap (253:6)
> devDataStore1-volMachines_snap-cow (253:5)
> L- (9:127)
> devDataStore2-volData (253:0)
> L- (259:6)
> devSystem-volRoot (253:3)
> L- (8:3)
> devSystem-volSwap (253:2)
> L- (8:3)
> $ cat /proc/meminfo | grep Dirty
> Dirty: 0 kB
In case someone will ask: During I/O, the value increased/decreased
as expected.
Zdenek Kabelac wrote:
> Note: you could always 'experiment' without lvm2 in the picture -
> you can ran 'fsfreeze --freeze|--unfreeze' yourself - to see whether
even
> this command is able to finish ?
fsfreeze caused the same problem :/
I also changed filesystem from xfs to ext4 just in case... same issue.
For testing I stopped the MDRAID and removed one NVMe disk which I
cleared and where I created a new ext4 partition. Running
$ fsfreeze --freeze /mnt/test
returned within seconds and I was unable do any I/O against /mnt/test
as expected.
I unfreezed the filesystem and started to copy ~50GB to the volume.
After waiting 5 minutes and verifying that /proc/meminfo didn't list
any 'dirty' pages, I re-run the fsfreeze command which caused the
same issue -- system hangs. :/
I will repeat the test with the other NVMe later...
So probably a kernel/driver issue or hardware problem.
--
Regards,
Thomas
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