[dm-devel] write directly to device mapper snapshot origin device ?
Mikulas Patocka
mpatocka at redhat.com
Fri Jul 15 13:50:25 UTC 2016
> Are origin devices readonly ?
>
> When i do dd if=/dev/zero of=/dev/mapper/ff count=10, it kills all the
> process says OOM.
>
> How do you go about debugging this ? I'm running 4.7.0-rc7+ .
Find some older kernel where this worked.
Use the git bisect tool on the kernel tree to find out which patch broke
it.
Mikulas
> root at vm-xenial-foo:~# dmsetup info
> Name: cryptie4-ff
> State: ACTIVE
> Read Ahead: 256
> Tables present: LIVE
> Open count: 0
> Event number: 0
> Major, minor: 251, 0
> Number of targets: 2
>
> Name: ff
> State: ACTIVE
> Read Ahead: 256
> Tables present: LIVE
> Open count: 0
> Event number: 0
> Major, minor: 251, 1
> Number of targets: 1
>
> root at vm-xenial-foo:~# dmsetup status
> cryptie4-ff: 0 102400 linear
> cryptie4-ff: 102400 122880 linear
> ff: 0 102400 snapshot-origin
> root at vm-xenial-foo:~#
>
>
>
>
> free -m
> total used free shared buff/cache available
> Mem: 7762 2178 3720 358 1864 4920
> Swap: 19145 0 19145
>
>
> --
> -- Navin
>
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