When the data volume is large, DataStage uses a scratch disk to process data. The default scratch disk space is usually the Scratch folder in the Server folder where the application is installed. To use a larger scratch disk space, we can create a custom configuration file.

The default configuration file is called default.apt and  sits in the Configuration folder (for example /opt/IBM/InformationServer/Server/Configuration/). In this folder, we can create a new configuration file (new_2node.apt). The example uses two nodes. Change the resource disk and resource scratch disk parameters as below.

{
    node "node1"
    {
        fastname "<Your DataStage Server URL>"
        pools ""
        resource disk "/scratch" {pools ""}
        resource scratchdisk "/scratch" {pools ""}
    }
    node "node2"
    {
        fastname "<Your DataStage Server URL>"
        pools ""
        resource disk "/scratch" {pools ""}
        resource scratchdisk "/scratch" {pools ""}
    }
}

Go back to the parallel job that gave the error. In the job parameter, add the variable APT_CONFIG_FILE and set the new config file path (/opt/IBM/InformationServer/Server/Configuration/new_2node.apt) in order to override the default config file path.

Check out the further reference here.