vzdump: config: improve description of ionice setting

The CFQ scheduler was removed with Linux 5.0 and ionice is now used
by the newer BFQ scheduler. Mention what the special value 8 does.
Also mention that for snapshot and suspend mode backups of VMs, the
setting only affects the compressor, because the kvm process is not a
child process of vzdump then and does not inherit the ionice priority.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>

diff --git a/src/PVE/VZDump/Common.pm b/src/PVE/VZDump/Common.pm
index 64c4e4ecc9cd10831fb0e7db8b5fc030a8d226e5..a6fe483a88c985fd5cc529e0c3b4906e4ebff5a3 100644 (file)
--- a/src/PVE/VZDump/Common.pm
+++ b/src/PVE/VZDump/Common.pm
@@ -212,7 +212,10 @@ my $confdesc = {
     },
     ionice => {
        type => 'integer',
-       description => "Set CFQ ionice priority.",
+       description => "Set IO priority when using the BFQ scheduler. For snapshot and suspend "
+           ."mode backups of VMs, this only affects the compressor. A value of 8 means the idle "
+           ."priority is used, otherwise the best-effort priority is used with the specified "
+           ."value.",
        optional => 1,
        minimum => 0,
        maximum => 8,