Storage unit selection criteria within a group
The storage unit selection determines the order in which the applied backup policy will be executed.
Choose from one of the following criteria.
Table: Storage unit selection criteria
Selection | Description |
|---|---|
Prioritized | If the Prioritized option is selected, NetBackup chooses the next available storage unit in the list for backup. Prioritized is the default selection. |
Failover | If the Failover option is selected, when a job must queue for a storage unit, the job queues rather than try another storage unit in the group |
Round robin | If the Round robin option is selected, NetBackup chooses the least recently selected storage unit in the list as each new job is started. If a storage unit is unavailable, NetBackup examines the next storage unit until it finds one that is available |
Media server load balancing | If the Media server load balancing option is selected, NetBackup selects a storage unit based on a capacity-managed approach. In this way, NetBackup avoids sending jobs to busy media servers. If a storage unit is unavailable, NetBackup examines the next storage unit until it finds one that is available. |
Reason why storage unit can be considered unavailable.
The storage unit is busy
The storage unit is down
The storage unit is out of media
The storage unit has no available space
The storage unit has reached the maximum concurrent job settings
The Media server load balancing option indicates that NetBackup select a storage unit based on a capacity-managed approach. In this way, NetBackup avoids sending jobs to busy media servers.
If a storage unit is unavailable, NetBackup examines the next storage unit until it finds one that is available.
The selection is based on the following factors:
The rank of the media server. NetBackup considers the number of processes that are running on each CPU along with the memory thresholds on each server to determine the rank of a media server. If the free memory drops below a determined threshold, or if the number of running processes per CPU rises over a determined threshold, then the overall rank of the media server drops.
The number of jobs on the media server. NetBackup considers the number of scheduled jobs on each media server.
Whether the media server has enough disk space to accommodate the estimated size of the image. (Physical and virtual tapes ignore this requirement.) NetBackup estimates the size of any of the new or any current jobs on each media server. It then determines whether the jobs fit on a given volume. NetBackup estimates the amount of space that the job may require, based on previous backup history. If no history is available, the high water mark for the storage unit serves as a guide.
Media server load balancing cannot be selected for a storage unit group that includes a Basic Disk storage unit. Also, a Basic Disk storage unit cannot be included in an existing storage unit group with Media server load balancing enabled.
Note:
It is recommended to select Media server load balancing for disk staging storage units within a storage unit group.