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

[Gionatan Danti]

Il 14-04-2017 19:36 Xen ha scritto:
> The thing is just dismounted apparently; I don't even know what causes 
> it.
> 

Maybe running "iotop -a" for some hours can point you to the right 
direction?

> The other volumes are thin. I am just very afraid of the thing filling
> up due to some runaway process or an error on my part.
> 
> If I have a 30GB volume and a 30GB snapshot of that volume, and if
> this volume is nearly empty and something starts filling it up, it
> will do twice the writes to the thin pool. Any damage done is doubled.
> 
> The only thing that could save you (me) at this point is a process
> instantly responding to some 90% full message and hoping it'd be in
> time. Of course I don't have this monitoring in place; everything
> requires work.

There is something similar already in place: when pool utilization is 
over 95%, lvmthin *should* try a (lazy) umount. Give a look here: 
https://www.redhat.com/archives/linux-lvm/2016-May/msg00042.html

Monitoring is a great thing; anyway, a safe fail policy would be *very* 
nice...

-- 
Danti Gionatan
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