partitioner hangs if libparted sees partitions for which device nodes don't exist

This is certainly a likely location for problems, but I'm afraid I can't reproduce this myself, which is probably necessary in order for me to fix it. Could you try this:

 * Start an installation attempt as before.
 * When you reach the hostname prompt, switch to Alt-F2, enter 'nano /lib/partman/automatically_partition/25replace/choices', change 'set -e' to 'set -ex', and save and exit.
 * Switch back to Alt-F1. Continue until it hangs.
 * Switch to Alt-F2. Kill all the process IDs listed in 'ps | egrep "partman|parted"', preferably in a single 'kill' command. (The idea of this is to force the full trace to be written out to the log file.)
 * Attach the full syslog and partman logs to this bug. There are two ways to extract them: either select "Save debug logs" from the installer main menu, or else run 'anna-install openssh-client-udeb' from a shell and then use scp to copy them from /var/log/ to another system.

Hi Colin,
  Logs attached as requested.
(I might be able to do another few tries in the next few hours today, but otherwise the next chance will probably be Friday).

Dave

jibel asked for hte output of pvdisplay/vgdisplay/lvdisplay - this is attached here, taken from alt-f2 from the installer CD.

The setup is relatively simple, virtio hard disk with a partition vda5 with the only physical volume, and in that one volume group (server1), and in that we have a root, swap_1 logical volumes for the server itself; note then we have an 'export' logical volume together with a snapshot of it.
(The 'export' used to be iSCSI exported and itself has a whole Ubuntu installation on).

Dave

For your fun and excitement, here is some strace op:

for the process shown as /bin/sh /lib/partman/automatically_partition/25repla

strce -ivp
[00914416] open("/var/lib/partman/infifo", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666

The two 10initial-auto processes are stuck in a read on fd 7 (a pipe)

The parted-server process is stuck in

[006ee416] open("/var/lib/partman/stopfifo", O_RDONLY

Dave

I took a regular LVM install of Maverick ubuntu-server and was able to install Natty ubuntu-server over it without any problems.

Are you sure you did that 'set -ex' edit? I'm not seeing the output from it, and that's the bit I really need.

Thinking about it, it wouldn't hurt to have the same 'set -ex' edit in /lib/partman/automatically_partition/15reuse/choices too.

Incidentally, the problem is not as you suggested on #ubuntu-testing that nothing is listening to the output of that script - what's happened is that the communication channel with parted_server has somehow got out of sync. That much I guessed from your initial report. The problem is determining exactly where that happened ...

I can reproduce the hang of partman with a partition on server1-export.
partman hangs in 35dump but I don't know exactly where yet because the output is buffered and the log is truncated.

This bug was fixed in the package partman-auto - 93ubuntu16

---------------
partman-auto (93ubuntu16) natty; urgency=low

  * If an LV contains a partition table, then libparted will see the
    partitions but device nodes won't be created for them, which broke the
    reuse and replace automatically_partition scripts. Tolerate this
    situation by ignoring device nodes that don't exist, or for which
    blockdev breaks in other ways (LP: #770041).
 -- Colin Watson <email address hidden> Tue, 26 Apr 2011 11:08:33 +0100

Hi,
  Just to confirm that on the release iso this works fine on the same VM. Thank you for the quick fix!

Dave