archive mirror
 help / color / mirror / Atom feed
From: cd <>
To: Zdenek Kabelac <>
Cc: LVM general discussion and development <>
Subject: Re: [linux-lvm] Creating/restoring snapshots in early userspace
Date: Mon, 08 Aug 2022 18:14:51 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

> Dne 07. 08. 22 v 22:38 cd napsal(a):
> > Hello,
> >
> > I have created some scripts which runs in the initramfs during the boot process. Very specifically, it's an initcpio runtime hook
> > Question: Is this a supported environment which to create/restore snapshots?
> >
> > When my script runs lvm lvconvert --merge testvg/lvmautosnap-root-1659902622-good
> > it appears to succeed (exit code is 0, and the restore appears to work properly). However, the following warnings appear in stderr as part of the restore process:
> >
> > /usr/bin/dmeventd: stat failed: No such file or directory
> > WARNING: Failed to unmonitor testvg/lvmautosnap-root-1659902622-good.
> > /usr/bin/dmeventd: stat failed: No such file or directory
> Hi
> Your initramfs likely needs to contain 'modified' version of your system's
> lvm.conf where 'monitoring' will be disabled (set to 0) - as you do not want
> to start your monitoring while you are operating in your ramdisk.
> Once you flip to your rootfs with your regular /etc/lvm/lvm.conf - you need
> to start monitoring of you activated LVs (vgchange --monitor y)
> > Merging of volume testvg/lvmautosnap-root-1659902622-good started.
> > /run/lvm/lvmpolld.socket: connect failed: No such file or directory
> Again a thing you do not want to run in your ramdisk - lvmpolld is another
> service/daemon you should run while you are in your rootfs.
> fully removed.
> > And I get similar errors when trying to create new volumes with lvm lvcreate --permission=r --snapshot --monitor n --name my_snapshot
> > /usr/bin/dmeventd: stat failed: No such file or directory
> >
> > In summary, I'm happy to just ignore the warning messages. I just want to make sure I'm not risking the integrity of the lvm volumes by modifying them during this part of the boot process.
> It looks like you are trying to do something in your ramdisk you really should
> be doing once you flip to your rootfs - ramdisk is purely meant to be used
> to get things 'booting' and flip to rootfs ASAP - doing things in your
> ramdisk which is really not a 'working environment' sounds like you are
> asking yourself for some big troubles with resolving error paths (i.e. using
> unmonitored devices like 'snapshot/mirror/raids/thin...' for longer period of
> time is simply 'bad design/plan' - switch to rootfs should happen quickly
> after you initiate things in your initramdfs...
> Regards
> Zdenek

Thanks for the insightful response. Indeed, setting monitoring = 0 in lvm.conf makes the warning messages go away. Interestingly, on arch, the initcpio hook for lvm2 _does_ attempt to set this setting:
with sed -i '/^\smonitoring =/s/1/0/' "${BUILDROOT}/etc/lvm/lvm.conf"

However, the sed pattern fails to match because the line is commented out in lvm.conf.
I've filed a bug with arch to address this:

Thanks again!

linux-lvm mailing list
read the LVM HOW-TO at

  reply	other threads:[~2022-08-08 18:23 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-07 20:38 [linux-lvm] Creating/restoring snapshots in early userspace cd
2022-08-08 10:57 ` Zdenek Kabelac
2022-08-08 18:14   ` cd [this message]
2022-08-08 19:17     ` Zdenek Kabelac

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='' \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).