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Local File Systems

The local file systems are available on each cluster compute node and dev-node. However, the files saved in each node are different from the others. Their introductions are below.

/tmp or /mnt/local

LOCAL space is a hard drive on a node. The files on this space can be accessed locally on each node without going through network. This space is a good choice for jobs using a single node or multiple nodes where I/O is processed only on each node's local file.  When network traffic is high, using this space will likely allow your program to run faster than running on HOME, RESEARCH or SCRATCH space. Please note that LOCAL space is shared with all processes running on the same node and there is no direct I/O from other nodes. The space also has no auto backup. It should be used as temporary storage space. When the execution of programs in a job is completed, any useful files in this space should be saved back to HOME or RESEARCH space.

$TMPDIR

TMPDIR directory is automatically created as/tmp/local/$SLURM_JOBID when your job starts on the local node and is deleted after it finishes.

/dev/shm

RAMDISK space is a “logical” storage space; it sits inside a node’s RAM, not disk. Linux supports a system tool that provides an interface for users to intercept the I/O requests to /dev/shm with memory operations.  We may think of it as a virtual disk in memory. Due to this nature, access to this space is actually access to RAM. Since the bandwidth of the access is much higher,  the I/O operations are considered faster than LOCAL space. However, since programs take up some of the node's memory, the usable RAM space for program execution becomes less. This space is good for programs that do not require large memory and perform very frequent I/O on small files.

Warning

Please limit the use of the local spaces. It is also used for MPI runtime to implement fast communication between MPI processes. Users are advised to clean up the space after use. The files that over 2 weeks old will be removed without notice. In the situation that the space is over 90% full, we may clean up those not currently used files without notice.