Managing Network Data Management Protocol

The Storwize V7000 Unified system supports Managing Network Data Management Protocol (NDMP), which is an open standard protocol for Network Attached Storage (NAS) backup and restore functions.

The Storwize V7000 Unified system supports NDMP version 4 provided by compatible Data Management Applications (DMAs) such as Symantec's Veritas NetBackup. Full and incremental backup and restore of file system data is provided by capturing data and metadata using file system snapshots. An NDMP backup session provides backup of a specific directory, a set of directories in a file system, or all of the files and subdirectories contained within a file system. Name length of files and directories that are backed up or restored using NDMP is limited to a maximum of 255 characters. Multiple directories within the same file system, and multiple file systems, can be backed up or restored concurrently. All extended attributes, including access control list (ACL) information, are also stored for every file and directory in a backup. File set information is not backed up or restored. An NDMP restore session restores all of the files and directories in the backed up structure along with their extended attributes, including ACL information. A snapshot is used to provide a point-in-time copy for a backup; it is the snapshot of the directory structure that is actually backed up. The use of a snapshot accounts for files that might be open or in use during the backup.

Note: A single file in the NDMP backup data stream can be restored using the NDMP Direct Access Restore (DAR) feature if DAR is supported by the Data Management Application (DMA). All metadata, including ACL information, is restored along with the file contents.

A full backup backs up all of the files and directories within the specified scope. An incremental backup backs up all of the files and directories in the specified scope that have been added, removed or changed since the last full backup. Incremental backups are cumulative; they contain all of the files and directories contained in the previous incremental backup, if one exists.

The NDMP function is configured and managed on the Storwize V7000 Unified system using the Storwize V7000 Unified command-line interface (CLI) from the active Management Node. NDMP alerts are written to the alert log on the Storwize V7000 Unified active file module. Viewing an alert log NDMP entry is the only Storwize V7000 Unified system NDMP feature that is accessible from the Storwize V7000 Unified graphical user interface (GUI).

Tip: Performing an NDMP backup operation on an Storwize V7000 Unified file system impacts the performance of other operations on that file system. Performance is decreased when the NDMP prefetch function is used. Performance decrease is minimized when an NDMP backup operation is performed while the Storwize V7000 Unified system is at its lowest utilization. NDMP backup duration increases as the number of files in the file system to be backed up increases, and can take a considerable amount of time, depending in part on external factors such as client I/O and other functions concurrently running on the Storwize V7000 Unified system. During incremental NDMP backups, file system metadata is scanned to determine which files to back up. If the directory being backed up is very large, there might be a delay before data starts transferring.

NDMP does not distinguish file sets. NDMP behaves as though a file set link point is a standard directory. A link point is restored by NDMP as a standard directory without any file set information. NDMP does not distinguish file clones. A file clone is backed up and restored by NDMP as a regular file, using the same amount of space as the clone parent.

There are two methods to backup an Storwize V7000 Unified system to an external IBM® IBM Spectrum Protect™ server. The preferred method is to use Storwize V7000 Unified native backup and restore commands with the embedded IBM Spectrum Protect backup client. The other method is the use of NDMP in conjunction with an external IBM Spectrum Protect server.