Methods for backing up and recovering data on NAS file servers accessed by CIFS protocol

The backup-archive client can process network-attached storage (NAS) file-server data that is accessed by using the Common Internet File System (CIFS) protocol.

You can use the following methods to back up and recover data on NAS devices:

• Use the backup-archive client to back up and restore data, by using CIFS to access files from the backup-archive client. Data can be stored on the IBM Spectrum Protect server with file-level granularity, by using the progressive-incremental backup method. The data is stored in the IBM Spectrum Protect storage hierarchy and can be migrated, reclaimed, and backed up to a copy storage pool.

  This method increases processor usage when the client accesses individual files. The method requires that the data to flow through the client. This method also requires that the data flows through the IBM Spectrum Protect server unless a LAN-free configuration is used.

• Use the snapdiff option to mitigate the performance problems of CIFS backup. This option stores data with file-level granularity by using progressive incremental backup for CIFS.
• Use a backup-archive client that is running on the NAS device, if you can use external programs with the NAS operating system.

  This method decreases processor usage of CIFS. Data can be stored on the IBM Spectrum Protect server with file-level granularity by using progressive-incremental backup. The data is stored in the IBM Spectrum Protect storage hierarchy and can be migrated, reclaimed, and backed up to a copy storage pool. This method requires that data flow through the backup-archive client. This method also requires that the data flows over a network and through the IBM Spectrum Protect server unless a LAN-free configuration is used.

• Use NDMP with the backup-archive client. File systems are backed up as full images (all files) or differential images (all files that changed since the last full backup). Backed up images are stored on a tape device that is accessed by the NAS file server. This method provides high performance because there is no data flow through a backup-archive client or IBM Spectrum Protect server. Data that is backed up to the server by using NDMP cannot be migrated, reclaimed, or backed up to a copy storage pool.

The following limitations exist for NAS file server data when it is accessed by using CIFS:

• File and directory security information might be inaccessible when the Windows account that is performing the backup is not a member of the Domain Administrators group of the domain the NAS file server is a trusted member of. It is also possible that these security access failures might prevent the entire file or directory from being backed up.
• Performance degradation occurs because data is being accessed remotely.
• The mapped drives appear to the client as NTFS file systems, but they might not have full NTFS functionality. For example, the encryption attribute of a file is set, but when the client backs up the file, the backup fails because the volume-level encryption setting indicates that encryption cannot be used for the volume. ReFS file systems also appear to the client as NTFS file systems.
  Tip: Use NDMP with the backup-archive client on a NAS file server to back up and restore volumes instead of backing up and restoring the volumes by using remote mapped drives.