When backup jobs are run for multiple virtual machines (VMs), VMs are backed up sequentially, with each VM backup on a separate job stream. The number of simultaneous job streams can be limited through configuration for the storage policy and subclient, and by the number of available data paths for a datastore or volume where backup data is being written.
By default, the next VM to be backed up and assigned to a job stream is selected randomly from the list of VMs that remain to be backed up. This default selection can lead to performance issues when most of the backup jobs are writing to the same datastore or volume.
For streaming backups (including Backup Copy for IntelliSnap), you can perform load balancing across datastores and volumes by setting nGetNextVMMethod on the Virtual Server Agent (VSA) proxy that performs the backup. When this parameter is set to 1, Commvault checks activity on datastores and volumes sequentially, based on each VM's primary datastore or volume, and selects the next virtual machine for backup for the datastore or volume with the smallest number of VMs being backed up by the current job.
To set the nGetNextVMMethod option:
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From the CommCell Browser, go to Client Computers > <VirtualizationClient>.
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Right-click the VSA proxy and select Properties.
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On the General tab of the Client Computer Properties dialog, click Advanced.
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On the Advanced Client Properties dialog, click the Additional Settings tab.
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Click Add.
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Add the following entry:
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Name: nGetNextVMMethod
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Category: Virtual Server
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Type: Integer
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Value: 1 (to perform load balancing across datastores and volumes)
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Click OK to save the additional setting.
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Click OK twice more to save the advanced client properties and the client properties.