[pve-devel] [PATCH qemu-server] fix #2408: use scsi-hd backend for iSCSI as well

[Stefan Reiter]

As mentioned in #2408, live-migrating a VM between storages that use
different scsi backends (scsi-hd, scsi-generic, scsi-block) breaks.

To fix, from QEMU 4.1 machine types onward (to not break current
behaviour any more), only use scsi-hd, as in recent versions, there is
almost no difference between the two anyway.

scsi-block (which potentially also breaks) requires a flag to be
manually set on the disk, so we can assume the user knows what they're
doing.

Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---

See also recent discussion on the mailing list:
https://pve.proxmox.com/pipermail/pve-devel/2019-September/039189.html

@Daniel Berteaud: You also mentioned using scsi-hd fixes #2335 (which you
already have submitted a patch for previously) and #2380. Is this correct?
Just for reference, so we can keep them in sync on the bugtracker.


 PVE/QemuServer.pm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 6d6e663..c5f46ef 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -1898,7 +1898,8 @@ sub print_drivedevice_full {
 		 $path = PVE::Storage::path($storecfg, $drive->{file});
 	    }
 
-	    if($path =~ m/^iscsi\:\/\//){
+	    if($path =~ m/^iscsi\:\/\// &&
+		!qemu_machine_feature_enabled($machine_type, undef, 4, 1)) {
 		$devicetype = 'generic';
 	    }
 	}
-- 
2.20.1