diff --git a/PVE/Storage.pm b/PVE/Storage.pm
index 3b86956..72458cf 100755
--- a/PVE/Storage.pm
+++ b/PVE/Storage.pm
@@ -211,6 +211,17 @@ sub storage_can_replicate {
     return $plugin->storage_can_replicate($scfg, $storeid, $format);
 }
 
+sub get_max_protected_backups {
+    my ($scfg, $storeid) = @_;
+
+    return $scfg->{'max-protected-backups'} if defined($scfg->{'max-protected-backups'});
+
+    my $rpcenv = PVE::RPCEnvironment::get();
+    my $authuser = $rpcenv->get_user();
+
+    return $rpcenv->check($authuser, "/storage/$storeid", ['Datastore.Allocate'], 1) ? -1 : 5;
+}
+
 sub storage_ids {
     my ($cfg) = @_;
 
@@ -240,6 +251,30 @@ sub update_volume_attribute {
     my $scfg = storage_config($cfg, $storeid);
     my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
 
+    my ($vtype, undef, $vmid) = $plugin->parse_volname($volname);
+    my $max_protected_backups = get_max_protected_backups($scfg, $storeid);
+
+    if (
+	$vtype eq 'backup'
+	&& $vmid
+	&& $attribute eq 'protected'
+	&& $value
+	&& !$plugin->get_volume_attribute($scfg, $storeid, $volname, 'protected')
+	&& $max_protected_backups > -1 # -1 is unlimited
+    ) {
+	my $backups = $plugin->list_volumes($storeid, $scfg, $vmid, ['backup']);
+	my ($backup_type) = map { $_->{subtype} } grep { $_->{volid} eq $volid } $backups->@*;
+
+	my $protected_count = grep {
+	    $_->{protected} && (!$backup_type || ($_->{subtype} && $_->{subtype} eq $backup_type))
+	} $backups->@*;
+
+	if ($max_protected_backups <= $protected_count) {
+	    die "The number of protected backups per guest is limited to $max_protected_backups ".
+		"on storage '$storeid'\n";
+	}
+    }
+
     return $plugin->update_volume_attribute($scfg, $storeid, $volname, $attribute, $value);
 }
 
diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
index c8caa41..7dac34b 100644
--- a/PVE/Storage/BTRFSPlugin.pm
+++ b/PVE/Storage/BTRFSPlugin.pm
@@ -67,7 +67,8 @@ sub options {
 	shared => { optional => 1 },
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
-	'prune-backups'=> { optional => 1 },
+	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	is_mountpoint => { optional => 1 },
diff --git a/PVE/Storage/CIFSPlugin.pm b/PVE/Storage/CIFSPlugin.pm
index d5efa5f..982040a 100644
--- a/PVE/Storage/CIFSPlugin.pm
+++ b/PVE/Storage/CIFSPlugin.pm
@@ -134,6 +134,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	username => { optional => 1 },
diff --git a/PVE/Storage/CephFSPlugin.pm b/PVE/Storage/CephFSPlugin.pm
index f75c1b8..4976747 100644
--- a/PVE/Storage/CephFSPlugin.pm
+++ b/PVE/Storage/CephFSPlugin.pm
@@ -155,6 +155,7 @@ sub options {
 	maxfiles => { optional => 1 },
 	keyring => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	'fs-name' => { optional => 1 },
     };
 }
diff --git a/PVE/Storage/DirPlugin.pm b/PVE/Storage/DirPlugin.pm
index c60818b..1baad63 100644
--- a/PVE/Storage/DirPlugin.pm
+++ b/PVE/Storage/DirPlugin.pm
@@ -58,6 +58,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	mkdir => { optional => 1 },
diff --git a/PVE/Storage/GlusterfsPlugin.pm b/PVE/Storage/GlusterfsPlugin.pm
index d8d2b88..ad386d2 100644
--- a/PVE/Storage/GlusterfsPlugin.pm
+++ b/PVE/Storage/GlusterfsPlugin.pm
@@ -133,6 +133,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	mkdir => { optional => 1 },
diff --git a/PVE/Storage/NFSPlugin.pm b/PVE/Storage/NFSPlugin.pm
index 0400c93..5bd7313 100644
--- a/PVE/Storage/NFSPlugin.pm
+++ b/PVE/Storage/NFSPlugin.pm
@@ -85,6 +85,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	options => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
diff --git a/PVE/Storage/PBSPlugin.pm b/PVE/Storage/PBSPlugin.pm
index 4b3f349..687901f 100644
--- a/PVE/Storage/PBSPlugin.pm
+++ b/PVE/Storage/PBSPlugin.pm
@@ -73,6 +73,7 @@ sub options {
 	'master-pubkey' => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	fingerprint => { optional => 1 },
     };
 }
diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
index 6673409..521e3e9 100644
--- a/PVE/Storage/Plugin.pm
+++ b/PVE/Storage/Plugin.pm
@@ -155,6 +155,13 @@ my $defaultData = {
 	    optional => 1,
 	},
 	'prune-backups' => get_standard_option('prune-backups'),
+	'max-protected-backups' => {
+	    description => "Maximal number of protected backups per guest. Use '-1' for unlimited.",
+	    type => 'integer',
+	    minimum => -1,
+	    optional => 1,
+	    default => "Unlimited for users with Datastore.Allocate privilege, 5 for other users",
+	},
 	shared => {
 	    description => "Mark storage as shared.",
 	    type => 'boolean',