[linux-lvm] Snapshot behavior on classic LVM vs ThinLVM

Gionatan Danti g.danti at assyoma.it
Fri Apr 14 09:55:21 UTC 2017

Il 14-04-2017 11:37 Zdenek Kabelac ha scritto:
> The problem is not with 'stopping' access - but to gain the access 
> back.
> So in this case - you need to run 'fsck' - and this fsck usually needs
> more space - and the complexity starts with - where to get this space.
> In the the 'most trivial' case - you have the space in 'VG' - you just
> extend thin-pool and you run 'fsck' and it works.
> But then there is number of cases ending with the case that you run
> out of metadata space that has the maximal size of ~16G so you can't
> even extend it, simply because it's unsupported to use any bigger
> size.
> So while every case has some way forward how to proceed - none of them
> could be easily automated.

To better understand: what would be the (manual) solution here, if 
metadata are full and can not be extended due to the hard 16 GB limit?

> And it's so much easier to monitor and prevent this to happen compared
> with solving these thing later.
> So all is needed is - user is aware what he is using and does proper
> action and proper time.

Absolutely. However, monitoring can also fail - a safe failure model is 
a really important thing.


Danti Gionatan
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Assyoma S.r.l. - www.assyoma.it
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