This section describes the mechanisms to start and stop the UnifyFS server processes within a job allocation.
Overall, the steps 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, one must start the UnifyFS server process (
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 reports 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 override any
/etc/unifyfs/unifyfs.conf. See UnifyFS Configuration
for further details on customizing the UnifyFS runtime configuration.
1#!/bin/bash 2 3# spillover data to node-local ssd storage 4export UNIFYFS_LOGIO_SPILL_DIR=/mnt/ssd/$USER/data 5 6# store server logs in job-specific scratch area 7export UNIFYFS_LOG_DIR=$JOBSCRATCH/logs 8 9unifyfs start --share-dir=/path/to/shared/file/system
unifyfs provides command-line options to select the shared file system path,
choose the client mountpoint, and control stage-in and stage-out of files.
The full usage for
unifyfs is as follows:
[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": -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 -t, --timeout=<sec> [OPTIONAL] wait <sec> until all servers become ready -S, --share-dir=<path> [REQUIRED] shared file system <path> for use by servers -c, --cleanup [OPTIONAL] clean up the UnifyFS storage upon server exit -i, --stage-in=<manifest> [OPTIONAL] stage in file(s) listed in <manifest> file -P, --stage-parallel [OPTIONAL] use parallel stage-in -T, --stage-timeout=<sec> [OPTIONAL] timeout for stage-in operation Command options for "terminate": -o, --stage-out=<manifest> [OPTIONAL] stage out file(s) listed in <manifest> on termination -P, --stage-parallel [OPTIONAL] use parallel stage-out -T, --stage-timeout=<sec> [OPTIONAL] timeout for stage-out operation -s, --script=<path> [OPTIONAL] <path> to custom termination script -S, --share-dir=<path> [REQUIRED for --stage-out] shared file system <path> for use by servers
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
under 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, use
unifyfs terminate to terminate the servers. Pass the
--cleanup option to
unifyfs start to have the servers remove temporary data locally stored on
each node after termination.
Resource Manager Job Integration
UnifyFS includes optional support for integrating directly with compatible resource managers to automatically start and stop servers at the beginning and end of a job when requested by users. Resource manager integration requires administrator privileges to deploy.
Currently, only IBM’s Platform LSF with Cluster System Manager (LSF-CSM)
is supported. LSF-CSM is the resource manager on the CORAL2 IBM systems
at ORNL and LLNL. The required job prologue and epilogue scripts, along
with a README documenting the installation instructions, is available
within the source repository at
Support for the SLURM resource manager is under development.
Transferring Data In and Out of UnifyFS
Data can be transferred in/out of UnifyFS during server startup and termination, or at any point during a job using two stand-alone applications.
Transfer at Server Start/Terminate
The transfer subsystem within UnifyFS can be invoked by providing the
-i|--stage-in option to
unifyfs start to transfer files into UnifyFS:
$ unifyfs start --stage-in=/path/to/input/manifest/file --share-dir=/path/to/shared/file/system
and/or by providing the
-o|--stage-out option to
to transfer files out of UnifyFS:
$ unifyfs terminate --stage-out=/path/to/output/manifest/file --share-dir=/path/to/shared/file/system
The argument to both staging options is the path to a manifest file that contains
the source and destination file pairs. Both stage-in and stage-out also require
UnifyFS’s file staging functionality requires a manifest file in order to move data.
The manifest file contains one or more file copy requests. Each line in the manifest corresponds to one transfer request, and it contains both the source and destination file paths. Directory copies are currently not supported.
Each line is formatted as:
<source filename> <whitespace> <destination filename>.
If either of the filenames contain whitespace or special characters, then both
filenames should be surrounded by double-quote characters (”) (ASCII character
The double-quote and linefeed end-of-line characters are not supported in any
filenames used in a manifest file. Any other characters are allowed,
including control characters. If a filename contains any characters that might
be misinterpreted, we suggest enclosing the filename in double-quotes.
Comment lines are also allowed, and are indicated by beginning a line with the
Here is an example of a valid stage-in manifest file:
$ [prompt] cat example_stage_in.manifest /scratch/users/me/input_data/input_1.dat /unifyfs/input/input_1.dat # example comment line /home/users/me/configuration/run_12345.conf /unifyfs/config/run_12345.conf "/home/users/me/file with space.dat" "/unifyfs/file with space.dat"
Transfer During Job
Data can also be transferred in/out of UnifyFS using the
helper program. This is the same program used internally by
provide file staging during server startup and termination.
The helper program can be invoked at any time while the UnifyFS servers are up and responding to requests. This allows for bringing in new input and/or transferring results out to be verified before the job terminates.
UnifyFS Stage Executable
unifyfs-stage program is installed in the same directory as the
unifyfs utility (i.e.,
A manifest file (see above) needs to be provided as an argument to use this approach.
[prompt]$ unifyfs-stage --help Usage: unifyfs-stage [OPTION]... <manifest file> Transfer files between unifyfs volume and external file system. The <manifest file> should contain list of files to be transferred, and each line should be formatted as /source/file/path /destination/file/path OR in the case of filenames with spaces or special characters: "/source/file/path" "/destination/file/path" One file per line; Specifying directories is not currently supported. Available options: -c, --checksum Verify md5 checksum for each transfer (default: off) -h, --help Print usage information -m, --mountpoint=<mnt> Use <mnt> as UnifyFS mountpoint (default: /unifyfs) -p, --parallel Transfer all files concurrently (default: off, use sequential transfers) -s, --skewed Use skewed data distribution for stage-in (default: off, use balanced distribution) -S, --status-file=<path> Create stage status file at <path> -v, --verbose Print verbose information (default: off) By default, each file in the manifest will be transferred in sequence (i.e., only a single file will be in transfer at any given time). If the '-p, --parallel' option is specified, files in the manifest will be transferred concurrently. The number of concurrent transfers is limited by the number of parallel ranks used to execute unifyfs-stage.
$ srun -N 1 -n 1 unifyfs-stage $MY_MANIFEST_FILE
$ srun -N 4 -n 8 unifyfs-stage --parallel $MY_MANIFEST_FILE
UnifyFS LS Executable
unifyfs-ls program is installed in the same directory as the
unifyfs utility (i.e.,
$UNIFYFS_INSTALL/bin). This tool will provide
information about any files the local server process knows about. Users
may find this helpful when debugging their applications and want to know if
the files they think are being managed by UnifyFS really are.
[prompt]$ unifyfs-ls --help Usage: unifyfs-ls [ -v | --verbose ] [ -m <dir_name> | --mount_point_dir=<dir_name> ] -v | --verbose: show verbose information(default: 0) -m | --mount_point: the location where unifyfs is mounted (default: /unifyfs)