Dell NetWorker Module for Databases and Applications 19.11 Administration Guide

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Configuring parallel backups

NMDA supports backups that are performed with multiple parallel sessions (also known as multiple streams, multiple channels, or multinode). This technology extracts multiple streams of data in parallel from a database, and writes them in parallel to one or more storage devices. This method can enhance performance when you back up or restore a large amount of data.

About this task

NOTE:The Orchestrated Application Protection feature does not support parallel backups. However, Orchestrated Application Protection supported database itself supports parallel backups. In this case, the database backup utility can still work with the parallel mode.

A parallel backup may lead to data multiplexing. Multiplexing is the NetWorker ability to write multiple backup streams simultaneously to the same storage device. NetWorker multiplexes backup streams when all the following conditions are true:

  • The NetWorker device type is not AFTD, Data Domain, or CloudBoost.
  • The number of parallel backup sessions is greater than the number of devices available for backup.
  • The target session value for the device is not 1.

The use of NetWorker multiplexing can improve backup performance, but it can adversely affect restore performance for Informix, Lotus, and Oracle.

CAUTION:Disable NetWorker multiplexing for DB2 backups and Sybase backups. Otherwise, the restore becomes suspended or fails.

You can disable NetWorker multiplexing by setting the number of backup sessions equal to the number of available storage devices, and by setting the target session value to 1 for those devices.

Parallel backups to AFTD, Data Domain, or CloudBoost devices are not multiplexed. However, the use of multiple concurrent streams to the same device can impact the overall throughput and deduplication ratio. Minimize the number of sessions to any device that includes deduplication by setting the target session attribute value of the device to 1. The NetWorker and Data Domain Boost Integration Guide and the latest version of the NetWorker with CloudBoost Integration Guide provide details.

To configure an NMDA parallel backup as either a manual or scheduled backup:

Steps

  1. Determine the number of available devices, the target sessions, and the maximum sessions per device for the backup.
  2. On the NetWorker server:
    1. Set the server parallelism in the NetWorker Server resource and the client parallelism in the NetWorker Client resource to a value greater than the number of sessions that are used for NMDA backups. Verifying the NetWorker Server resource and Configuring the Client resource describe the parallelism setting.
    2. If required, create a Device resource for each device according to Verifying the NetWorker Device resource.
    3. For DB2 and Sybase backups, disable NetWorker multiplexing.
  3. Use the instructions in the following topics to specify the number of sessions (parallelism) for a backup:
    NOTE:The backup parallelism must not be greater than the total number of device sessions that are available for the backup through the media pool configuration, as determined in step 1. Otherwise, the backup becomes suspended because it is waiting for an available device to be mounted for the proper pool, or if not enough devices are available, the backup fails .

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