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Each cluster node comes with its own disk space which is chosen by user. If your task requires locally accessible space such as /tmp, each node's disk space might be the best option for speed. Data stored in the local disk space of each node disappear when the node is destroyed, i.e., when the cluster is erased. The external NAS space can be mounted in any cluster nodes. However, it is expected for users to mount the NAS space in the cluster master node to bring required data and codes to the cluster NFS partition. The external NAS disk space is backuped, and it is not erased when the cluster is erased. Therefore, the external NAS space can be also used to store results produced in your task by copying results stored in the NFS partition to the mounted external disk space. The cluster NFS partition is available in all cluster nodes. Therefore, the NFS partition is a right place to host files that need to be accessed in all cluster nodes. The NFS partition is also destroyed when the cluster is erased. If you need to execute specific commands such as changing file permission and creating new directories in all cluster nodes, see the example given in "Executing custom commands in multiple VM nodes" of the useful tips.
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