[PATCH qemu-server v1] {pbs-,vma-}restore: disable caching for LVM-thin

[PATCH qemu-server v1] {pbs-,vma-}restore: disable caching for LVM-thin

[Markus Frank]

Mitigate performance issues with LVM-thin by disabling the page cache
when restoring to LVM-thin storage.

This reduces the time taken for a restore to LVM-thin by approximately
half.

A user has reported that their iSCSI LUNs cannot handle the number of
requests generated by 4k block writes when using pbs-restore with
caching enabled.

Signed-off-by: Markus Frank <m.frank@proxmox.com>
---
 src/PVE/QemuServer.pm | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index 149f17be..3e3d9bfb 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -7092,7 +7092,9 @@ sub restore_proxmox_backup_archive {
             # TODO: extending this needs a separate rationale, the amplification
             # avoided here is specific to the volblock layout
             my $target_scfg = PVE::Storage::storage_config($storecfg, $d->{storeid});
-            push @$pbs_restore_cmd, '--no-cache' if $target_scfg->{type} eq 'zfspool';
+            if ($target_scfg->{type} eq 'zfspool' || $target_scfg->{type} eq 'lvmthin') {
+                push @$pbs_restore_cmd, '--no-cache';
+            }
 
             my $dbg_cmdstring = PVE::Tools::cmd2string($pbs_restore_cmd);
             print "restore proxmox backup image: $dbg_cmdstring\n";
@@ -7674,7 +7676,10 @@ sub restore_vma_archive {
 
             # TODO: extending this needs a separate rationale, the amplification
             # avoided here is specific to the volblock layout
-            my $cache_none = $scfg->{type} eq 'zfspool' ? ':cache=none' : '';
+            my $cache_none = '';
+            if ($scfg->{type} eq 'zfspool' || $scfg->{type} eq 'lvmthin') {
+                $cache_none = ':cache=none';
+            }
 
             print $fifofh
                 "${map_opts}format=$d->{format}${cache_none}:${write_zeros}:$d->{devname}=$path\n";
-- 
2.47.3