[linux-lvm] Running thin_trim before activating a thin pool

[Demi Marie Obenour]

On Mon, Jan 31, 2022 at 12:02:23PM +0100, Gionatan Danti wrote:
> Il 2022-01-29 18:45 Demi Marie Obenour ha scritto:
> > Is it possible to configure LVM2 so that it runs thin_trim before it
> > activates a thin pool?  Qubes OS currently runs blkdiscard on every thin
> > volume before deleting it, which is slow and unreliable.  Would running
> > thin_trim during system startup provide a better alternative?
> 
> I think that, if anything, it would be worse: a long discard during boot can
> be problematic, even leading to timeout on starting other services.
> After all, blkdiscard should be faster then something done at higher level.

thin_trim is a userspace tool that works on an entire thin pool, and I
suspect it may be significantly faster than blkdiscard of an individual
thin volume.  That said, what I would *really* like is something
equivalent to fstrim for thin volumes: a tool that works asynchronously,
in the background, without disrupting concurrent I/O.

> -- 
> Danti Gionatan
> Supporto Tecnico
> Assyoma S.r.l. - www.assyoma.it
> email: g.danti at assyoma.it - info at assyoma.it
> GPG public key ID: FF5F32A8

FYI, you might want to specify a full fingerprint here; short key IDs
are highly vulnerable to collision and preimage attacks.

-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab
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