Optimizing backup operations
To help optimize virtual machine (VM) backup operations, adjust the settings for the vmmaxparallel option. With this option, you can optimize backup operations without adversely affecting Hyper-V hosts.
Overview of the backup options
The following information provides an overview of the vmmaxparallel and vmmaxbackupsessions options and factors to consider when you are configuring these options for performance.
You might also want to complete backup operations for a limited number of VMs by using the default values and then increase the values if you want to decrease the backup time for the remaining VMs.
In general, increasing the option value results in improved network throughput. However, at a certain point, increasing this value will no longer increase performance. For example, if a 1 GB network is used, when the network is saturated, the throughput will not increase if the option value is increased. In addition, the increased values might result in a higher CPU utilization that negatively affects resource availability on the host.
Also, if network and processor resources are shared with other operations, higher option values might also adversely affect performance on those operations. For example, if the network that is used for backup operations is also used for regular network traffic by the VMs, the VMs might experience slower network speeds during backup operations.
If your priority is to improve throughput, increase the default values. If your priority is to minimize impact to the hosts, decrease the values.
- vmmaxparallel
- The vmmaxparallel option is used to control the maximum number of VMs that can
be backed up at any one time. The optimal value for vmmaxparallel depends on the
processing power of the Hyper-V host and the performance of I/O between the host and the IBM Spectrum Protect server.
For example, if you are moving data to the server over a busy or slow LAN, you might have to limit the number of VMs in each parallel backup operation.
Similarly, if the Hyper-V host processing capabilities are limited for any reason, you might also want to limit the number of VMs.
To help optimize performance, use a minimum of a 10GB network in your Data Protection for Microsoft Hyper-V environment.
- vmmaxbackupsessions
- The vmmaxbackupsessions option is used to control the maximum number of data
movement sessions that can be included in the backup operation at any one time. Although this option
sets the maximum number of sessions that are allowed, the data mover that is running on the Hyper-V
host determines the actual number of sessions that are required based on the incoming workload and
uses that number.
The value of the vmmaxbackupsessions option must be equal to or greater than the value of the vmmaxparallel option. If the value is less than the value of the vmmaxparallel option, a message is returned and the value is changed to the same value as vmmaxparallel option. This change ensures that there are as many sessions as there are VMs.
You might have to experiment to find the optimum value for the vmmaxbackupsessions option. Each dispatched VM is guaranteed one session and then extra sessions are applied to the dispatched VMs. The number of sessions will not exceed the value that is specified by the vmmaxbackupsessions option.
The benefit of increasing the vmmaxbackupsessions option value is limited if your storage system performance is slower than the available network speed between the data mover and the server.