As you know an Avamar client requires memory, CPU and network resources in order to perform a backup. The reason is simple. We are talking about source-deduplication. Most things are done at the client. Throttling Avamar CPU and network utilization is done by the avtar process. Avtar is the primary process for backups and restores. Avtar communicates with the gsan processes on the storage nodes.
Note: By default, the Avamar client's avtar process will use as much network bandwidth and CPU cycles as are made available to it by the operating system.
CPU utilization: If a backup runs during a time of day where the client machine is under heavy production load it may be considered desirable to throttle avtar's CPU utilization in order to ensure that CPU cycles remain available for other system services. When trottle down the CPU utilization the longer the backup takes before completing.
Avtar CPU utilization can be reviewed in the Avamar client backup log as shown below:
To implement this, edit the avtar.cmd file found in the Avamar client's avs/var directory. Create a new avtar.cmd file if one does not already exist. The entry made in the file should be in the following format, where '60' is the maximum average percentage of CPU that the avtar process should use. (In my example)
Network utilization: The same arguments apply here as for CPU utilization.
To implement this, edit the avtar.cmd file found in the Avamar client's avs/var directory. Create a new avtar.cmd file if one does not already exist. The entry made in the file should be in the following format.
When implemented, avtar will pause as long as necessary after sending each packet in order to ensure that network usage does not exceed the specified maximum bandwidth (specified in mega bits per second)
--throttle=50 uses half a 100Mbps connection
When you are done changing, save the avtar.cmd file, restart the client agent from the client GUI (Operations > Advanced > Restart Client agent, in Windows) and run the backup.
Please use the throttle flags with CAUTION and bear the following in mind:-
- Processes normally run as fast as they can. If we attempt to lower the CPU utilisation of the client processes, then the backup may run MUCH slower than it otherwise would and may not complete in time for the backup window.
- If we slow down the process, other clients which are queueing to start their backups will be delayed by the lengthened backup time of this client.
- If the client is performing other work at the time of the Avamar backup, this work will be impacted less but for a longer period of time.
If in doubt about the suitability of applying the flags discussed below, contact your EMC Professional Services representative.