Allow parallel execution of NAS backup and delete commands

api/src/main/java/org/apache/cloudstack/backup/BackupManager.java

@@ -59,6 +59,12 @@ public interface BackupManager extends BackupService, Configurable, PluggableSer
             "false",
             "Enable volume attach/detach operations for VMs that are assigned to Backup Offerings.", true);
 
+    ConfigKey<Boolean> NASBackupParallelExecution = new ConfigKey<>("Advanced", Boolean.class,
+            "backup.nas.parallel.execution.enabled",
+            "true",
+            "Allow NAS take-backup commands to run in parallel with other backup and delete commands on the KVM host. Disable to force sequential execution.",
+            true, ConfigKey.Scope.Zone);
+
     /**
      * List backup provider offerings
      * @param zoneId zone id

core/src/main/java/org/apache/cloudstack/backup/TakeBackupCommand.java

@@ -32,6 +32,7 @@ public class TakeBackupCommand extends Command {
     private List<String> volumePaths;
     @LogLevel(LogLevel.Log4jLevel.Off)
     private String mountOptions;
+    private boolean executeInSequence = false;
 
     public TakeBackupCommand(String vmName, String backupPath) {
         super();
@@ -89,6 +90,13 @@ public void setVolumePaths(List<String> volumePaths) {
 
     @Override
     public boolean executeInSequence() {
-        return true;
+        // Parallel by default: each backup uses its own per-VM on-NAS path, so concurrent
+        // runs do not contend. Operators can force sequential execution per zone via the
+        // backup.nas.parallel.execution.enabled setting.
+        return executeInSequence;
+    }
+
+    public void setExecuteInSequence(boolean executeInSequence) {
+        this.executeInSequence = executeInSequence;
     }
 }

core/src/test/java/org/apache/cloudstack/backup/TakeBackupCommandTest.java

@@ -0,0 +1,41 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+package org.apache.cloudstack.backup;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TakeBackupCommandTest {
+
+    @Test
+    public void testExecuteInSequenceDefaultsToParallel() {
+        TakeBackupCommand command = new TakeBackupCommand("vm-1", "/backups/vm-1");
+        // Default: run in parallel with other backup/delete commands.
+        Assert.assertFalse(command.executeInSequence());
+    }
+
+    @Test
+    public void testExecuteInSequenceIsSettable() {
+        TakeBackupCommand command = new TakeBackupCommand("vm-1", "/backups/vm-1");
+
+        command.setExecuteInSequence(true);
+        Assert.assertTrue(command.executeInSequence());
+
+        command.setExecuteInSequence(false);
+        Assert.assertFalse(command.executeInSequence());
+    }
+}

plugins/backup/nas/src/main/java/org/apache/cloudstack/backup/NASBackupProvider.java

@@ -159,6 +159,7 @@ public boolean takeBackup(final VirtualMachine vm) {
         command.setBackupRepoType(backupRepository.getType());
         command.setBackupRepoAddress(backupRepository.getAddress());
         command.setMountOptions(backupRepository.getMountOptions());
+        command.setExecuteInSequence(!BackupManager.NASBackupParallelExecution.valueIn(vm.getDataCenterId()));
 
         if (VirtualMachine.State.Stopped.equals(vm.getState())) {
             List<VolumeVO> vmVolumes = volumeDao.findByInstance(vm.getId());

server/src/main/java/org/apache/cloudstack/backup/BackupManagerImpl.java

@@ -1023,7 +1023,8 @@ public ConfigKey<?>[] getConfigKeys() {
                 BackupFrameworkEnabled,
                 BackupProviderPlugin,
                 BackupSyncPollingInterval,
-                BackupEnableAttachDetachVolumes
+                BackupEnableAttachDetachVolumes,
+                NASBackupParallelExecution
         };
     }