Comment 28 for bug 1429327

Revision history for this message
Mauricio Faria de Oliveira (mfo) wrote : Re: Boot from an unique, stable, multipath-dependent symlink

Hi Mathieu,

(I have no idea what the 3 attachments above are related to. :-)

This is the patch missing for the installer.
I did some testing and noticed some problems w/ it, which made me to reconsider how/if we should really make this based on an UUID= field. Let me describe the issue.

IIRC, if this one is applied, and one or more partitions on multipath disks are used (so there are some UUID=multipath-<uuid> on /etc/fstab), the init jobs for the local filesystems wouldn't finish.
I couldn't investigate further by the time, but I guess the problem is some pieces maybe just don't assume they should pick a symlink from /dev/disk/by-uuid/, and perhaps search for the UUID field in the filesystem itself, which obviously doesn't contain the 'multipath-' prefix).

So, maybe better ways are either to move back to explicitly using /dev/disk/by-id/ (and then 'multipath-' prefix would be OK, as it's not a filesystem field, AFAICT), or use different approaches -- I believe upstream multipath-tools relies on different things, which are probably worth checking.

I guess that for W, the most interesting thing is to consider moving to upstream multipath-tools. I know there's a Debian-base to think of (and I see they still modify the sources to use mpath[0-9]+ rather than mpath[a-z]+, which creates some difficulties for some backporting..).. but at some time, either Ubuntu or Debian should make the move to have better multipath support, and by looking at the number of fixes made after 0.5.0, I think git HEAD is a very good place to sit on nowadays (besides it -- VPD page 0x80 as optional -- is important for IBM IPR controllers..).

This seems something that can span interesting things to talk about :)