Media server load balancing
The 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 BasicDisk storage unit. Also, a BasicDisk storage unit cannot be included in an existing storage unit group with Media server load balancing enabled.
The following methods also work to distribute the backup workload:
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Adjust the backup load on a media server. |
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Distribute the backup load on media servers during peak periods. |
Reconfigure policy schedules so that they write backups to storage units on the media servers that can handle the load (assuming that master servers and media servers are on separate hosts). |
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Adjust the backup load on the client. |
Change the Maximum jobs per client global attribute. For example, raising the Maximum jobs per client limit increases the number of concurrent jobs that any one client can process and therefore increases the load.
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Reduce the time that is needed to back up clients. |
Increase the number of jobs that clients can perform concurrently, or use multiplexing. Another possibility is to increase the number of jobs that the media server can perform concurrently for the policies that back up the clients. |
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Give preference to a policy. |
Increase the Limit jobs per policy attribute for the preferred policy relative to other policies. Or, increase the priority for the policy.
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Adjust the load between fast and slow networks. |
Increase the Limit jobs per policy and Maximum jobs per client for policies and clients in a faster network. Decrease these numbers for slower networks. Another solution is to use the NetBackup capability to limit bandwidth.
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Maximize the use of devices. |
Use multiplexing. Allow as many concurrent jobs per storage unit, policy, and client as possible without causing server, client, or network performance problems. |
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Prevent backups from monopolizing tape devices. |
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