This article describes how the Networker server selects the volume which helps user understand the backup operation provided by Networker software.

For most of entry-level users, it’s little difficult to understand how the Networker select the backup volume or device. This might impact user to configure Networker backup rules and policies which may eventually affect the qualities of customer’s data backup and recovery. This article is going to provide a brief introduction about how the Networker server selects a volume.

Firstly, once a backup takes place, the NetWorker server searches for a volume from the appropriate pools to accept the data for backup. Whatever it’s psychical disk, tape or EMC Data Domain system. We all need to configure how to backup data to the device, and if it’s reasonable to allocate to different kinds of devices. So when configure Networker backup, user have to confirm which target device in the pool. Once the configuration complete and backup job start, how many available devices are in its pool? The available volumes are as follows:

·         Mounted on stand-alone devices.

·         Available for labeling and accessible to the NetWorker server through Auto Media Management or a library.

·         Labeled for the appropriate pool and already mounted in a device, or are available for mounting, if a library is being used.

If two or more volumes from the appropriate pool are available, the server uses this hierarchy to select a volume:

·         Mounted volumes from the appropriate pool with the mode appendable are selected. This includes newly labeled volumes. If more than one mounted volume is appendable, the server uses this hierarchy: Device availability. The server writes to the volume from the appropriate pool that is mounted on the device with the fewest current sessions. Volume label time. The server writes to the volume with the oldest label time if the mounted volumes are appendable and session availability is not an issue.

·         If a library is in use and there is no mounted, appendable volume in the library, the server determines whether there is an unmounted, appendable volume available. This includes newly labeled volumes.

·         If multiple unmounted, appendable volumes are available, the volume with the oldest label time is selected.

·         If no mounted volumes are appendable and Auto Media Management is enabled, a mounted volume with the mode recyclable is selected. The server relabels and mounts the volume.

·         If a stand-alone device is being used and Auto Media Management is not enabled, the server sends a mount request notification.

·         If a library is in use and no unmounted, appendable volumes exist, the server determines whether there is an unmounted, recyclable volume.

·         If Auto Media Management is not enabled, or if there are no appendable or recyclable volumes, the server sends a mount request notification.

In summary, whether there is any available volume in the destination pool, Networker server still precedes the backup according the rule to select available volume. User need to configure volume distribution appropriately to keep backup efficiency.

Author: Fenglin Li

iEMC APJ

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