[pve-devel] [RFC PATCH guest-common 1/2] ReplicationState: purge state from non local vms
Fabian Grünbichler
f.gruenbichler at proxmox.com
Thu Jun 2 16:33:34 CEST 2022
On May 24, 2022 1:41 pm, Dominik Csapak wrote:
> when running replication, we don't want to keep replication states for
> non-local vms. Normally this would not be a problem, since on migration,
> we transfer the states anyway, but when the ha-manager steals a vm, it
> cannot do that. In that case, having an old state lying around is
> harmful, since the code does not expect the state to be out-of-sync
> with the actual snapshots on disk.
>
> One such problem is the following:
>
> Replicate vm 100 from node A to node B and C, and activate HA. When node
> A dies, it will be relocated to e.g. node B and start replicate from
> there. If node B now had an old state lying around for it's sync to node
> C, it might delete the common base snapshots of B and C and cannot sync
> again.
>
> Deleting the state for all non local guests fixes that issue, since it
> always starts fresh, and the potentially existing old state cannot be
> valid anyway since we just relocated the vm here (from a dead node).
>
> Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
the logic seems sound, the state *is* invalid/outdated once the guest
has been stolen..
Reviewed-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
> ---
> i tested it in various configurations and with live migration, offline
> migration, ha relocation etc. and did not find an issue, but since
> the check was already there and commented out, maybe someone has a
> better idea why this might not be a good thing, so sending as RFC
>
> src/PVE/ReplicationState.pm | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/PVE/ReplicationState.pm b/src/PVE/ReplicationState.pm
> index 0a5e410..8eebb42 100644
> --- a/src/PVE/ReplicationState.pm
> +++ b/src/PVE/ReplicationState.pm
> @@ -215,7 +215,7 @@ sub purge_old_states {
> my $tid = $plugin->get_unique_target_id($jobcfg);
> my $vmid = $jobcfg->{guest};
> $used_tids->{$vmid}->{$tid} = 1
> - if defined($vms->{ids}->{$vmid}); # && $vms->{ids}->{$vmid}->{node} eq $local_node;
> + if defined($vms->{ids}->{$vmid}) && $vms->{ids}->{$vmid}->{node} eq $local_node;
> }
>
> my $purge_state = sub {
> --
> 2.30.2
>
>
>
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