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Load Balancing Operations between Libraries

Table of Contents

Overview

The software system includes many features that help you to balance the operations between available storage resources in the CommCell. For example:

  • You may find that a specific MediaAgent over loaded or slow and hence you may want to configure the MediaAgent in such a way that a only a specific number of jobs use the MediaAgent at any given time, while re-directing the overflow jobs to other MediaAgents in the CommCell.
  • You may want more jobs to use a specific MediaAgent with a library that has faster and/or more number of drives, then MediaAgents with libraries that have slower and/ or fewer drives.
  • You may want to utilize all storage resources in the CommCell, so that all data protection operations are completed in the specific operation window.

This document describes how to configure the MediaAgent software to distribute the load between multiple resources.

Load Balancing Using Spill and Fill

The spill and fill method equally distributes the jobs among available resources.

The following example illustrates the spill and fill mechanism between tape and disk libraries:

In this example, 2 MediaAgents have been configured with tape libraries, while 2 more MediaAgents have 2 disk libraries configured. Such a configuration would result in the following data paths:

  • MediaAgent 1 -> Tape Library 1 -> Drive Pool 1 -> 3 drives
  • MediaAgent 2 -> Tape Library 2 -> Drive Pool 1 -> 3 drives
  • MediaAgent 3 -> Disk Library 1 - >Mount Path 1
  • MediaAgent 4 -> Disk Library 2 - >Mount Path 1

To perform load-balancing between these 4 MediaAgents, in such a way that at any given time 2 jobs write to the disk library, while using all the drives in the tape libraries. This can be done by as follows:

  • Setting the maximum number of writers to 2 in the disk libraries.
  • Allocating the maximum number of drives (3 in this example) in the drive pools associated with the tape library.
  • Setting the criteria for using the alternate data path as spill and fill .

This ensures that the jobs are distributed equally among all the MediaAgents.

See Also: Load balance (Spill and fill) between Data Paths.

Load Balancing between Disk Libraries

You can perform a simple load-balancing between 2 mount paths in a disk library, without using alternate data paths. This can be done using the Mount Path Allocation Policy in disk libraries and mount paths.

The following example illustrates this mechanism.

In this example, MediaAgent A has a disk library containing 2 mount paths. To perform load-balancing between these 2 mount paths, in such a way that at any given time 5 jobs write to the disk library, you can:

  • Define the Mount Path Allocation Policy at the disk library to 10.
  • Define the Mount Path Allocation Policy at each of the mount path to 5.

In the above example, (assuming that several jobs are running concurrently at a given time) the first five jobs will use mount path 1, and the next five jobs will use mount path 2. Subsequent jobs in the queue will be routed to either one of the mount paths, as soon as a mount path is freed.

Once the maximum allocated writers are used, the system will constantly check for an available resource, and as soon as one is freed the next job in the queue will be automatically routed to use that resource.