Dell NetWorker 19.9 Administration Guide

Staging save sets

Staging is the process of transferring backup data from one storage device, usually an AFTD to another device, and then removing the data from the original device. Staging save sets from the primary data device ensures that there is always sufficient disk space available on the primary device to store data.

To manage the staging process, manually stage individual save sets from a command prompt or you can configure a Staging resource that automatically stages the data. The Staging resource defines the criteria that the stage process uses to determine when the data device requires data staging and which save sets are eligible to stage and in what order.

Based on the configuration of the Staging resource, the staging process performs the following high level activities:

1. Performs file system checks at an interval that is defined in the File system check interval attribute to determine:
   • If the percentage of used disk space on the source device exceeds the value that is defined in the High water mark attribute of the Staging resource.
   • If the length of time that the save sets have resided on the disk exceeds the value that is defined in the Max storage period attribute of the Staging resource.
2. Creates a list of save sets on the source device that are eligible to move to a destination device.
3. Clones the eligible save sets from the source device to the destination device, and then updates the media database with information about the save sets on the destination device. The save set on the destination device retain the same attributes values, for example retention policy, as the original save set.
4. Removes the original save sets from the source device, recovers disk space on the source volume for staged save sets, and then removes information about the original save sets from the media database.
   NOTE:When the staging process encounters an error after successfully cloning some save sets, the staging process only removes successfully staged save sets from the source volume before the process ends. Only a single set of save sets will exist on either the source or destination volumes after staging.

Staging data allows you to accommodate multiple service levels. You can configure a staging policy that keep the most recent backups on one storage device for fast recovery and move other backups with less demanding recovery requirements to more cost-effective slower storage. For example, you can store the initial backup data on a high performance file type or advanced file type device to reduce backup time. At a later time, outside of the normal backup period, you use the staging process to move the data to a less expensive but more permanent storage medium, such as magnetic tape. After the backup data moves to the other storage medium, NetWorker deletes the backup data from the file or advanced file type device so that sufficient disk space is available for the next backup. Staging does not affect the retention policy of backup data and the staged data is still available for recovery on the destination device.

You can stage a save set from one disk to another as many times as required. For example, you could stage a save set from disk 1 to disk 2 to disk 3, and finally to a remote tape device. When the save set is staged to a tape, it cannot be staged again. However, you could still clone the tape.