Setting the Number of Parallel Data Streams

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Setting the Number of Parallel Data Streams

ISM supports up to four parallel data streams. You can adjust the number of data streams that can be active at one time. When you set this value, it allows you to specify the number of save sets that are backed up to the ISM server simultaneously. Backing up save sets in parallel allows your storage devices to operate at their most efficient levels because they receive a steady stream of data, which is written onto your storage volumes. For example, suppose that you have four storage devices and set the number of parallel data streams to four. During a backup to all four devices, each device receives one data stream.

To set or adjust the number of data streams that can be backed up in parallel

To display the ISM server properties, use the following command:
```
ism_show -config
```
The parallelism field in the ism_show -config output indicates the number of parallel data streams.
To change the number of parallel data streams, use the following command:
```
ism_config -streams #datastreams
```
To back up only one data stream at a time, set the value to 1.
```
ism_config -streams 1
```

In the following situations, adjust the number of data streams that you back up in parallel:

The ISM server is taking too long to back up all the data streams.
Increase the number of data streams.
The ISM server is so busy backing up data streams that it is not available for any other tasks.
Decrease the number of data streams.
The ISM server runs out of swap space or memory.
Decrease the number of data streams.