[pve-devel] migrate local -> drbd fails with vanished job

[Fabian Ebner]

Am 26.11.21 um 14:03 schrieb Roland Kammerer:
> Dear PVE devs,
> 
> While most of our users start with fresh VMs on DRBD storage, from time
> to time people try to migrate a local VM to DRBD storage. This currently fails.
> Migrating VMs from DRBD to DRBD works.

Hi,
there also is a forum thread about this [0]. It seems like the newly 
allocated disks are slightly bigger on the target DRBD storage. Just a 
hunch, but it does sounds similar to [1].

[0]: 
https://forum.proxmox.com/threads/online-migration-disk-move-problem.100171

[1]: https://bugzilla.proxmox.com/show_bug.cgi?id=3227#c8

> 
> I added some debug code to PVE/QemuServer.pm, which looks like the location
> things go wrong, or at least where I saw them going wrong:
> 
> root at pve:/usr/share/perl5/PVE# diff -Nur QemuServer.pm{.orig,}
> --- QemuServer.pm.orig  2021-11-26 11:27:28.879989894 +0100
> +++ QemuServer.pm       2021-11-26 11:26:30.490988789 +0100
> @@ -7390,6 +7390,8 @@
>       $completion //= 'complete';
>       $op //= "mirror";
> 
> +    print "$vmid, $vmiddst, $jobs, $completion, $qga, $op \n";
> +    { use Data::Dumper; print Dumper($jobs); };
>       eval {
>          my $err_complete = 0;
> 
> @@ -7419,6 +7421,7 @@
>                      next;
>                  }
> 
> +               print "vanished: $vanished\n"; # same as !defined($jobs)
>                  die "$job_id: '$op' has been cancelled\n" if !defined($job);
> 
>                  my $busy = $job->{busy};
> 
> 
> With that in place, I try to live migrate the running VM from node "pve" to
> "pvf":
> 
> 2021-11-26 11:29:10 starting migration of VM 100 to node 'pvf' (xx.xx.xx.xx)
> 2021-11-26 11:29:10 found local disk 'local-lvm:vm-100-disk-0' (in current VM config)
> 2021-11-26 11:29:10 starting VM 100 on remote node 'pvf'
> 2021-11-26 11:29:18 volume 'local-lvm:vm-100-disk-0' is 'drbdstorage:vm-100-disk-1' on the target
> 2021-11-26 11:29:18 start remote tunnel
> 2021-11-26 11:29:19 ssh tunnel ver 1
> 2021-11-26 11:29:19 starting storage migration
> 2021-11-26 11:29:19 scsi0: start migration to nbd:unix:/run/qemu-server/100_nbd.migrate:exportname=drive-scsi0
> drive mirror is starting for drive-scsi0
> Use of uninitialized value $qga in concatenation (.) or string at /usr/share/perl5/PVE/QemuServer.pm line 7393.
> 100, 100, HASH(0x557b44474a80), skip, , mirror
> $VAR1 = {
>            'drive-scsi0' => {}
>          };
> vanished: 1
> drive-scsi0: Cancelling block job
> drive-scsi0: Done.
> 2021-11-26 11:29:19 ERROR: online migrate failure - block job (mirror) error: drive-scsi0: 'mirror' has been cancelled
> 2021-11-26 11:29:19 aborting phase 2 - cleanup resources
> 2021-11-26 11:29:19 migrate_cancel
> 2021-11-26 11:29:22 ERROR: migration finished with problems (duration 00:00:12)
> TASK ERROR: migration problems
> 
> What I also see on "pvf" is that the plugin actually creates the DRBD block
> device, and "something" even tries to write data to it, as the DRBD devices
> auto-promotes to Primary.
> 
> Any hints how I can debug that further? The block device should be ready at
> that point. What is going on in the background here?
> 
> FWIW the plugin can be found here:
> https://github.com/linbit/linstor-proxmox
> 
> Regards, rck
> 
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