diff --git a/PVE/Storage.pm b/PVE/Storage.pm
index a2f400c..bd6e15e 100755
--- a/PVE/Storage.pm
+++ b/PVE/Storage.pm
@@ -41,11 +41,11 @@ use PVE::Storage::DRBDPlugin;
 use PVE::Storage::PBSPlugin;
 
 # Storage API version. Increment it on changes in storage API interface.
-use constant APIVER => 7;
+use constant APIVER => 8;
 # Age is the number of versions we're backward compatible with.
 # This is like having 'current=APIVER' and age='APIAGE' in libtool,
 # see https://www.gnu.org/software/libtool/manual/html_node/Libtool-versioning.html
-use constant APIAGE => 6;
+use constant APIAGE => 7;
 
 # load standard plugins
 PVE::Storage::DirPlugin->register();
diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
index b4f3be8..fe56864 100644
--- a/PVE/Storage/Plugin.pm
+++ b/PVE/Storage/Plugin.pm
@@ -82,15 +82,7 @@ our $prune_backups_format = {
 		       'than one backup for a single year, only the latest one is kept.'
     },
 };
-PVE::JSONSchema::register_format('prune-backups', $prune_backups_format, \&validate_prune_backups);
-sub validate_prune_backups {
-    my ($keep) = @_;
-
-    die "at least one keep-option must be set and positive\n"
-	if !grep { $_ } values %{$keep};
-
-    return $keep;
-}
+PVE::JSONSchema::register_format('prune-backups', $prune_backups_format);
 register_standard_option('prune-backups', {
     description => "The retention options with shorter intervals are processed first " .
 		   "with --keep-last being the very first one. Each option covers a " .