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File Recovery Methods

You can use the following methods to recover files from Virtual Server Agent backups:

  • Guest Agent
  • Agentless
  • Live File Recovery

Guest Agent

You can restore files using an agent installed in the destination client or virtual machine. This option supports recovery of larger amounts of data and generally offers the best performance, but it may not always be possible.

Supported Hypervisors

All hypervisors

Prerequisites

  • For Windows clients:
    • The destination client must have a Windows File System Agent installed (in full or restore-only mode). For more information, refer to Installing Restore Only Agents.
    • The version of the file system agent must be the same as the version of the Virtual Server Agent.
  • For Linux clients:
    • The destination client must have a UNIX File System Agent installed (in full or restore-only mode). Existing deployments using an Image Level Agent (deprecated) are also supported.

Notes

For Linux clients:

  • The Preserve Source Paths option is not supported when you are restoring files or folders from a virtual machine.
  • The Restore ACLs option restores basic user/group/world permissions and timestamps; advanced permissions are only restored when using a guest agent together with a File Recovery Enabler for Linux.
  • If the original user for a folder does not exist on the destination, restored files will have the user ID instead of the user name. Otherwise, folder user names and permissions are preserved.
  • Symbolic links can be restored if the source files are also restored, but they will use the timestamp of the restore operation instead of the original timestamp. If the source files are not restored, symbolic link files are restored but without links; as a result the linked data cannot be read.
  • Hard link files can be restored; if source files are also restored any corresponding link files use the same index node (inode).

Agentless

Agentless restores can be used to restore small files and folders into a virtual machine without installing an agent on the destination client. Using this option simplifies deployment and reduces the impact of backup and restore operations for virtual machines that do not have high transaction rates and large data requirements. This option is preferred in cases where the CommServe system or MediaAgent is not able to communicate with the VM (for example, in a restricted network).

Supported Hypervisors

  • Microsoft Hyper-V
  • VMware

Prerequisites

  • Microsoft Hyper-V requirements:
    • The Hyper-V host must be running on a Windows 2012 R2 server operating system.
    • The destination VM must be running on Windows 2008 R2 with Service Pack 1 or later, or on later versions of the operating system such as Windows 2012 or Windows 2012 R2.
    • The destination VM must be powered on.
    • Make sure that the latest integration services are running on the destination VM.
    • Enable Guest file services on the destination VM. If not enabled, the restore operation will enable the services.

      Note: A proxy cannot make two or more simultaneous parallel connections to the same VM. The restore to the VM for the job that establishes the first connection succeeds, but because an active connection exists between the proxy and the VM, subsequent jobs fail with a connection error.

  • VMware requirements:
    • For Windows, the virtual machine must have the NTFS file system.
    • The destination machine must meet the following prerequisites:
      • To verify the version of VMware software that is required to support this feature, see System Requirements.
      • The virtual machine must be powered on.
      • The latest release of VMware Tools must be installed and running.

        You can use open-vm-tools on guest VMs running supported Linux releases; open-vm-tools must be installed and running.

    • The user account that is used to browse the destination VM must have write permissions for the VM. To test this permission, see VMware KB article 2079098.

Notes

  • A proxy cannot make two or more simultaneous parallel connections to the same VM. The restore to the VM for the job that establishes the first connection succeeds, and subsequent jobs fail with a connection error because there is already an active connection between the proxy and the VM.
  • Windows VMs:
    • The Restore ACLs option is not supported for Windows VMs.
  • Linux VMs:
    • The Restore ACLs option only restores basic user/group/world permissions; advanced permissions are not restored. Timestamps are only restored when using agentless restores together with a File Recovery Enabler for Linux.
    • Permissions for guest files and folders are retained only when the user running the restore operation has permissions to change group ownership on the restored files and folders. If the user does not have change group ownership permissions, the restored files and folders are owned by the user who performed the restore.
    • You cannot restore an empty folder unless you restore the parent folder; when you restore a parent folder all other folders contained in the parent folder are also restored. 
    • Symbolic links can be restored if the source files are also restored, but they will use the timestamp of the restore operation instead of the original timestamp. If the source files are not restored, symbolic link files are restored but without links; as a result the linked data cannot be read.
    • Hard link files can be restored; if source files are also restored any corresponding link files use the same index node (inode).

Live File Recovery

Live File Recovery provides expanded file system support, including ext4, and enables live browse of backup data without requiring granular metadata collection during backups.

Live File Recovery can be used when reducing backup times is a priority. This is a tradeoff. You can perform backups without collecting metadata, reducing backup time but increasing the time required to browse files and folders.

Live file recovery supports restores of files and folders from backups of Windows VMs that use NTFS, ReFS, FAT, and FAT32 file systems, and of UNIX VMs that use ext2, ext3, ext4, XFS, JFS, HFS, HFS Plus, or Btrfs file systems.

Note: This method was originally introduced as a feature called Live File Recovery for VMware restores. It is now the default method for guest file and folder restores for all hypervisors except Docker.

Supported Hypervisors

All hypervisors except Docker

Prerequisites

  • To browse and recover files from a guest VM running Windows 2012 R2, select a VSA proxy and MediaAgent that is Windows Server 2012 R2 or later.
  • To restore UNIX files for ext4, XFS, JFS, HFS, HFS Plus, or Btrfs file systems in addition to ext2 and ext3 files, you must deploy and use a File Recovery Enabler for Linux to access the data in the backup.

    For Commvault Service Pack 7 and later, MediaAgents that are able to act as File Recovery Enablers are automatically configured.

  • To support Live File Recovery when the Virtual Server Agent and MediaAgent are deployed on different machines, the Virtual Server Agent must also be installed on the MediaAgent, even if a different MediaAgent is used for data movement. Otherwise, the MediaAgent is not included in the Use MediaAgent list in the Advanced Options tab of the Browse and Restore Options dialog box. You must provide data access for the MediaAgent in one of the following ways:
  • To enable Live File Recovery even when the Collect File Details option is selected for a subclient, you can configure the nEnforceLivebrowse additional setting on the Virtual Server Agent (VSA) proxy.

Notes

  • Do not use live file recovery for very large numbers of files (over a million). Instead, install a guest agent and ensure that source files are organized into multiple directories.
  • Live file recovery is only supported for recovery from backups using magnetic disk libraries, and is not supported from backups to tape libraries or virtual tape libraries.
  • Browsing speed is affected by network latency and the complexity of the file system being browsed.
  • If there is no activity on the VM for a specified time (10 minutes by default), the browse times out and the VM is unregistered. Once the cleanup is done, the restore job is marked as complete.
  • Live browse and file recovery operations are not supported for XFS realtime subvolumes.
  • With Service Pack 8 or later, live browse and recovery is supported for subvolumes of Btrfs file systems.
  • Windows VMs:
    • For Windows guest VMs, the Windows MediaAgent that is used for browse and restore operations must have the Virtual Server Agent installed.
    • Use Live File Recovery to restore files that have been dehydrated by Windows deduplication. A MediaAgent running Windows 2012 R2 or later, with the Virtual Server Agent installed and with the Windows deduplication role enabled, must be used as the VSA proxy when restoring the dehydrated files.
    • Windows Storage Spaces: You can perform a live browse to view and restore guest files and folders, with the following requirements and limitations:
      • The VSA proxy or MediaAgent that is used for the live browse must be running on Windows Server 2012 or later.
      • The MediaAgent that is used for the live browse cannot be part of a clustered environment.
      • Dynamic disk configuration on the virtual disk for a storage pool is not supported.
      • You cannot simultaneously browse two cloned VMs that use the same storage space information.
      • Live browse of Windows storage spaces is only supported for streaming backups, auxiliary copies, and backup copies, and not directly from IntelliSnap backups.
  • Linux VMs:
    • For Linux guest VMs, a File Recovery Enabler for Linux can be used as a MediaAgent to browse and restore data from backups of UNIX VMs.
    • For UNIX file restores, the restore operation uses the File Recovery Enabler for Linux that hosts the backup (if one is available) or the default File Recovery Enabler for Linux for the virtual server instance.
    • Browsing fails if the file system on the source VM for the backup is not supported by the File Recovery Enabler for Linux.
    • Initial mount during browse may take some time if the VM snapshot contains an inconsistent file system that requires fsck (file system check). A restore that follows the browse in quick succession does not incur that overhead because it reuses the mount point.
    • When you perform a live browse operation on Linux files and folders, the Client tab shows logical volumes as volume groups rather than mount paths.
    • Some special files from UNIX systems cannot be restored to a Windows system. These include symbolic link files, socket files, character device files, block files, and pipe files (FIFOs).
    • A virtual machine that contains the File Recovery Enabler for Linux can be included in backups, and the full VM can be restored; but you cannot recover files from the VM.
    • Logical volume manager (LVM) metadata processing for volumes encrypted using BitLocker is currently not supported. Decrypting contents of such volumes may not be feasible during browse or restore operations because decryption requires a recovery password or a decryption key. Because enumeration for the volume fails, a file-level browse operation for the encrypted volume cannot display file information.
    • When used with agentless restores, the Restore ACLs option only restores basic user/group/world permissions and timestamps. Advanced permissions are only restored when using a guest agent together with a File Recovery Enabler for Linux.
    • The Preserve Source Paths option is not supported when you are restoring files or folders from a virtual machine.
    • Permissions for guest files and folders are retained only when the user running the restore operation has permissions to change group ownership on the restored files and folders. If the user does not have change group ownership permissions, the restored files and folders are owned by the user who performed the restore.
    • You cannot restore an empty folder unless you restore the parent folder. When you restore a parent folder all other folders contained in the parent folder are also restored. 
    • Symbolic links can be restored if the source files are also restored, but they will use the timestamp of the restore operation instead of the original timestamp. If the source files are not restored, symbolic link files are restored but without links; as a result the linked data cannot be read.
    • Hard link files can be restored; if source files are also restored any corresponding link files use the same index node (inode).

Last modified: 12/12/2018 1:57:45 PM