Re: [linux-lvm] Silence Pool Check Overprovisioning Warnings

From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Silence Pool Check Overprovisioning Warnings
Date: Fri, 6 May 2022 06:04:43 -0400	[thread overview]
Message-ID: <YnTy6x+B6pmQFXSS@itl-email> (raw)
In-Reply-To: <CA+QLa9BupRpP00xSpaKMwCvvsWtH=Q=_Z7hwuX1A7o8VsFNgWg@mail.gmail.com>

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On Thu, May 05, 2022 at 12:11:29PM -0400, Robert Simmons wrote:
> Greetings,
> 
> I knowingly overprovision storage pools. I have careful monitoring of the
> overall free space in the storage pool, and the snapshots that I take for a
> particular volume are ephemeral. They're only related to a particular
> reverse engineering task. Once the task is complete, all the snapshots are
> deleted. There are a set of warnings that are generated
> during pool_check_overprovisioning here:
> 
> https://github.com/lvmteam/lvm2/blob/f70d97b91620bc7c2e5c5ccc39913c54379322c2/lib/metadata/thin_manip.c#L413-L428
> 
> The second, third, and fourth warnings are printed
> via log_print_unless_silent but the first is printed via log_warn. I would
> like an option that would silence all four of these warnings. If all four
> were logged via log_print_unless_silent, there would still be the problem
> of what other very useful warnings would I be silencing. This would be a
> suboptimal fix. I have read one proposed fix that appears to be optimal for
> my use case: adding an envvar "LVM_SUPPRESS_POOL_WARNINGS". This was
> proposed by zkabelac at redhat.com here:
> https://listman.redhat.com/archives/linux-lvm/2017-September/024332.html
> 
> What would be the next steps to getting this option implemented?
> 
> I see that there have been two threads about these warnings in the past:
> https://listman.redhat.com/archives/linux-lvm/2016-April/023529.html
> https://listman.redhat.com/archives/linux-lvm/2017-September/024323.html
> 
> One issue in the bug tracker that I can find:
> https://bugzilla.redhat.com/show_bug.cgi?id=1465974
> 
> Finally, we have a thread going about our use case over at Proxmox here:
> https://forum.proxmox.com/threads/solved-you-have-not-turned-on-protection-against-thin-pools-running-out-of-space.91055/

The Qubes OS developers (myself included) would also like a solution.
In Qubes OS, LVM is invoked by a python daemon which currently uses an
ugly regex hack to strip that line out of LVM’s stderr before asserting
that LVM’s stderr is empty.

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

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