[DRBD-user] Linstor - snapshot mouting

Gábor Hernádi gabor.hernadi at linbit.com
Mon Jun 17 08:53:54 CEST 2019


Hello,

> I wonder if it's safe to mount lvm snapshot after `linstor snapshot
create` command ...

Linstor can restore a snapshot into a new resource. If you now have a DRBD
on top of LVM, create a snapshot of that, modify the data without DRBD
knowing (as there is no DRBD running on top of a snapshot, only on the
"original" resource), restore that snapshot into a new resource, you will
certainly get into a situation you really don't want to be in.

> and why it creates lv snapshot with k flag?

The k flag is used for the lvchange command, not for creation. If an
administrator does not just deactivate a VG or that specific LV but also
sets the "activationskip" flag for our LV (like `lvchange -ky
drbdpool/test`, which will also have a 'k' attribute in the output of lvs)
then a simple `lvchange -ay drbdpool/test` will not activate the LV (that
means the device /dev/drbdpool/test is not created). Using `lvchange -ay -k
drbdpool/test` will ignore the "activationskip" flag, and will activate
that LV for us.

Hope that answers your question.

-- 
Best regards,
Gabor Hernadi
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