Starting & Stopping in a Job¶
In this section, we describe the mechanisms for starting and stopping UnifyFS in a user’s job allocation.
Overall, the steps taken to run an application with UnifyFS include:
- Allocate nodes using the system resource manager (i.e., start a job)
- Update any desired UnifyFS server configuration settings
- Start UnifyFS servers on each allocated node using
- Run one or more UnifyFS-enabled applications
- Terminate the UnifyFS servers using
First, we need to start the UnifyFS server daemon (
unifyfsd) on the nodes in
the job allocation. UnifyFS provides the
unifyfs command line utility to
simplify this action on systems with supported resource managers. The easiest
way to determine if you are using a supported system is to run
unifyfs start within an interactive job allocation. If no compatible
resource management system is detected, the utility will report an error message
to that effect.
start mode, the
unifyfs utility automatically detects the allocated
nodes and launches a server on each node. For example, the following script
could be used to launch the
unifyfsd servers with a customized
configuration. On systems with resource managers that propagate environment
settings to compute nodes, the environment variables will override any
/etc/unifyfs/unifyfs.conf. See UnifyFS Configuration
for further details on customizing the UnifyFS runtime configuration.
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#!/bin/bash # spillover checkpoint data to node-local ssd storage export UNIFYFS_SPILLOVER_DATA_DIR=/mnt/ssd/$USER/data export UNIFYFS_SPILLOVER_META_DIR=/mnt/ssd/$USER/meta # store server logs in job-specific scratch area export UNIFYFS_LOG_DIR=$JOBSCRATCH/logs unifyfs start --share-dir=/path/to/shared/file/system &
unifyfs provides command-line options to choose the client mountpoint,
adjust the consistency model, and control stage-in and stage-out of files.
The full usage for
unifyfs is as follows:
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[prompt]$ unifyfs --help Usage: unifyfs <command> [options...] <command> should be one of the following: start start the UnifyFS server daemons terminate terminate the UnifyFS server daemons Common options: -d, --debug enable debug output -h, --help print usage Command options for "start": -c, --cleanup [OPTIONAL] clean up the UnifyFS storage upon server exit -C, --consistency=<model> [OPTIONAL] consistency model (NONE | LAMINATED | POSIX) -e, --exe=<path> [OPTIONAL] <path> where unifyfsd is installed -m, --mount=<path> [OPTIONAL] mount UnifyFS at <path> -s, --script=<path> [OPTIONAL] <path> to custom launch script -S, --share-dir=<path> [REQUIRED] shared file system <path> for use by servers -i, --stage-in=<path> [OPTIONAL] stage in file(s) at <path> -o, --stage-out=<path> [OPTIONAL] stage out file(s) to <path> on termination Command options for "terminate": -s, --script=<path> <path> to custom termination script
After UnifyFS servers have been successfully started, you may run your
UnifyFS-enabled applications as you normally would (e.g., using mpirun).
Only applications that explicitly call
unifyfs_mount() and access files
with the specified mountpoint prefix will utilize UnifyFS for their I/O. All
other applications will operate unchanged.
After all UnifyFS-enabled applications have completed running, you should
unifyfs terminate to terminate the servers. Typically, one would pass
--cleanup option to
unifyfs start to have the servers remove
temporary data locally stored on each node after termination.