[pve-devel] [PATCH qemu-server] refuse to migrate volume-chain-snapshots for now

* [pve-devel] [PATCH qemu-server] refuse to migrate volume-chain-snapshots for now
@ 2025-07-18 11:56 Wolfgang Bumiller
  2025-07-18 12:30 ` [pve-devel] applied: " Thomas Lamprecht
  0 siblings, 1 reply; 2+ messages in thread
From: Wolfgang Bumiller @ 2025-07-18 11:56 UTC (permalink / raw)
  To: pve-devel

When using qcow2 "backing volumes" for snapshots we'd have to copy all
of them for local-storage migration. Let's refuse to do this for now
and wait until we decide whether this should also happen via
replication at some point.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
 src/PVE/QemuMigrate.pm | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/PVE/QemuMigrate.pm b/src/PVE/QemuMigrate.pm
index f46bdf40..251fcc79 100644
--- a/src/PVE/QemuMigrate.pm
+++ b/src/PVE/QemuMigrate.pm
@@ -454,6 +454,10 @@ sub scan_local_volumes {
 
                 # we cannot migrate snapshots on local storage
                 # exceptions: 'zfspool' or 'qcow2' files (on directory storage)
+                #
+                # Note that only qcow2 with in-qcow2 snapshots work - for
+                # backing-chain snapshots we'd need to copy the entire snapshot
+                # list (or support replication)
 
                 die "online storage migration not possible if non-replicated snapshot exists\n"
                     if $self->{running} && !$local_volumes->{$volid}->{replicated};
@@ -464,7 +468,8 @@ sub scan_local_volumes {
                 if (!(
                     $scfg->{type} eq 'zfspool'
                     || ($scfg->{type} eq 'btrfs' && $local_volumes->{$volid}->{format} eq 'raw')
-                    || $local_volumes->{$volid}->{format} eq 'qcow2'
+                    || ($local_volumes->{$volid}->{format} eq 'qcow2'
+                        && !$scfg->{'snapshot-as-volume-chain'})
                 )) {
                     die "non-migratable snapshot exists\n";
                 }
-- 
2.47.2



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