Shared Storage with NFS and SSHFS

File Sharing

Up to this point, my series on HPC fundamentals has covered PDSH, to run commands in parallel across a cluster's nodes, and Lmod, to allow users to manage their environment so they can specify various versions of compilers, libraries, and tools for building and executing applications. One missing piece is how to share files across a cluster's nodes.

File sharing is one of the cornerstones of client-server computing, HPC, and many other architectures. You can perhaps get away without it, but life just won't be easy any more. This situation is true for clusters of two nodes or clusters of thousands of nodes. A shared filesystem allows all of the nodes to "see" the exact same data as all other nodes. For example, if a file is updated on cluster node03, the updates show up on all of the other cluster nodes, as well.

Fundamentally, being able to share the same data with a number of clients is very appealing because it saves space (capacity), ensures that every client has the latest data, improves data management, and, overall, makes your work a lot easier. The price, however, is that you now have to administer and manage a central file server, as well as the client tools that allow the data to be accessed.

Although you can find many shared filesystem solutions, I like to keep things simple until something more complex is needed. A great way to set up file sharing uses one of two solutions: the Network File System (NFS) or SSH File System (SSHFS).

NFS

NFS, the most widely used HPC filesystem, is very easy to set up and performs reasonably well for small to medium-sized clusters as the primary storage. You can even use it for larger clusters if your applications don't read and write to it (e.g., /home).

The classic NFS approach to a shared directory is to export a directory or directories from the NFS server to compute nodes (clients). In general, any

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