[PATCH cluster 02/19] datacenter config: backup concurrency: add cluster-wide limit

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

Nodes run their part of a backup job on their own, so how many guests
are backed up at the same time depends on how many nodes the guests of
a job are spread over. In larger clusters this can overload shared
storages and backup servers, while lowering the per-node limit to
protect them slows down jobs whose guests are mostly on one node.

Add an optional limit for the whole cluster, enforced by the backup
code of all nodes together.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 src/PVE/DataCenterConfig.pm | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/PVE/DataCenterConfig.pm b/src/PVE/DataCenterConfig.pm
index baff829..f6ac5b9 100644
--- a/src/PVE/DataCenterConfig.pm
+++ b/src/PVE/DataCenterConfig.pm
@@ -229,6 +229,13 @@ my $backup_concurrency_format = {
         default_key => 1,
         optional => 1,
     },
+    cluster => {
+        type => 'integer',
+        description =>
+            "Maximal number of guests backed up at the same time in the whole cluster.",
+        minimum => 1,
+        optional => 1,
+    },
 };
 
 my $u2f_format = {
-- 
2.47.3