Hello,
I have investigated this problem again today. What seems to be causing
the regression is a change [1] adding support for device activation when
systemd is not present.
More specifically, this hunk [2] makes udev able to activate LVM devices
in the initramfs (systemd does not run in the initramfs in Ubuntu for
now):
TEST!="/run/systemd/system", GOTO="lvm_direct_vgchange"
[...]
LABEL="lvm_direct_vgchange"
ENV{LVM_VG_NAME_COMPLETE}=="?*", RUN+="(LVM_EXEC)/lvm vgchange -aay
--autoactivation event $env{LVM_VG_NAME_COMPLETE}"
GOTO="lvm_end"
In the actual root filesystem, multipath and lvm2 compete for taking
ownership of the block devices and there are measures in place (more or
less robust) to give preference to multipath.
OTOH, in the initramfs (of the installer), we currently only have the
LVM stack, not the multipath stack. Therefore, LVM freely takes
ownership of /dev/sda, /dev/sdb (assuming those are the block devices
involved).
The regression was introduced between the 22.04 and 22.10 releases, when
we bumped lvm2 to 2.03.16-1.
As mentioned here:
> Found a possible fix for this bug
> ===========================
>
> I tried adding multipath module to the installer initrd via initramfs-tools.
> This had the effect of
> initializing multipath during early initrd and before dm-multipath and lvm
> were initialized. With this
> change ( also a possible bug fix in initramfs-tools described below ) the
> dm-multipath disks were
> properly probed and recognized by probert.
having the multipath stack in the initramfs could be a way to address
the issue. The package multipath-tools-boot provides a possible
implementation. However, if stopping multipathd is a problem, I suppose
we could use a different implementation where we only rely on multipath,
not multipathd.
I suspect it might be easier to go back to the behavior we had in 22.04,
where LVM does not run in the initramfs. Maybe we don't entirely drop
the "new" udev rules but disable them when booting the installer, if
that is possible.
[1]
https://salsa.debian.org/lvm-team/lvm2/-/commit/2340adad4b3875331be1ba7abba881cc1b6e6738#b3d5381b3f503956bf78fdc525b656292a304bf4
[2] https://paste.ubuntu.com/p/2qHK5xNJzV/
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https://bugs.launchpad.net/bugs/2080474
Title:
ubuntu installation failing for systems having SAN disk
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