PowerProtect Data Manager 19.16 File System User Guide

Configure asset multi-streaming for file-based backups

PowerProtect Data Manager supports asset multi-streaming, which enables you to run a file system backup of an asset in parallel streams to reduce the time required to complete the file-based backup. Asset multi-streaming is enabled by default.

When using asset multi-streaming for file-based backups of large volumes, the contents of the volumes are divided into chunks. These chunks are backed up in parallel in multiple streams to increase the backup throughput.

The chunk size is a configurable parameter, with a default value of 50 GB (--chunkersize=50). The number of parallel streams is set by the --max-host-streams parameter in the configuration file, or the -M command-line option, as described in Configure the file system parallel backup setting. The value for number of parallel streams set in the config file takes precedence over the value set in the CLI. The number of streams is set per host (and not per asset), and each asset uses the streams available to it.

Creating chunks and multi-streaming the backup consumes some extra computing resources. You can control that usage by tuning the chunkersize and --max-host-streams parameters. If, after tuning, you are still not satisfied with the resource usage, you can disable multi-streaming. To do so, add the --disable-asset-multistreaming=true parameter in the configuration file, .ddfssv.fsagentconfig under the Settings folder.

Multi-streaming may not yield desired results in the following scenarios:

• System has limited CPUs or memory.
• Reads are slow, in which case, CPU usage will be high. For disks with slow read or high latency, disable multi-streaming.
• You are backing up many small files. Multi-streaming gives better performance when files are large. Many small files can cause undesirably high CPU usage levels.

Recommendations for optimal performance:

• Multi-streaming can be CPU-intensive. It is important to tune the environment for optimal chunk size and an optimal number of streams.
• If there are more volumes than streams in a protection policy, disable asset multi-streaming.