UnifyFS Configuration¶

Here, we explain how users can customize the runtime behavior of UnifyFS. In particular, UnifyFS provides the following ways to configure:

Configuration file: $INSTALL_PREFIX/etc/unifyfs/unifyfs.conf
Environment variables
Command line options to unifyfsd

All configuration settings have corresponding environment variables, but only certain settings have command line options. When defined via multiple methods, the command line options have the highest priority, followed by environment variables, and finally config file options from unifyfs.conf.

The system-wide configuration file is used by default when available. However, users can specify a custom location for the configuration file using the -f command-line option to unifyfsd (see below). There is a sample unifyfs.conf file in the installation directory under etc/unifyfs/. This file is also available in the extras directory in the source repository.

The unified method for providing configuration control is adapted from CONFIGURATOR. Configuration settings are grouped within named sections, and each setting consists of a key-value pair with one of the following types:

BOOL: 0|1, y|n, Y|N, yes|no, true|false, on|off

FLOAT: scalars convertible to C double, or compatible expression

INT: scalars convertible to C long, or compatible expression

STRING: quoted character string

unifyfs.conf¶

unifyfs.conf specifies the system-wide configuration options. The file is written in INI language format, as supported by the inih parser.

The config file has several sections, each with a few key-value settings. In this description, we use section.key as shorthand for the name of a given section and key.

`[unifyfs]` section - main configuration settings¶
Key	Type	Description
cleanup	BOOL	cleanup storage on server exit (default: off)
configfile	STRING	path to custom configuration file
daemonize	BOOL	enable server daemonization (default: off)
mountpoint	STRING	mountpoint path prefix (default: /unifyfs)

`[client]` section - client settings¶
Key	Type	Description
cwd	STRING	effective starting current working directory
fsync_persist	BOOL	persist data to storage on fsync() (default: on)
local_extents	BOOL	service reads from local data if possible (default: off)
max_files	INT	maximum number of open files per client process (default: 128)
super_magic	BOOL	whether to return UNIFYFS (on) or TMPFS (off) statfs magic (default: on)
write_index_size	INT	maximum size (B) of memory buffer for storing write log metadata
write_sync	BOOL	sync data to server after every write (default: off)

The cwd setting is used to emulate the behavior one expects when changing into a working directory before starting a job and then using relative file names within the application. If set, the application changes its working directory to the value specified in cwd when unifyfs_mount() is called. The value specified in cwd must be within the directory space of the UnifyFS mount point.

Enabling the local_extents optimization may significantly improve read performance for extents written by the same process. However, it should not be used by applications in which different processes write to the same byte offset within a file, nor should it be used with applications that truncate files.

`[log]` section - logging settings¶
Key	Type	Description
dir	STRING	path to directory to contain server log file
file	STRING	log file base name (rank will be appended)
on_error	BOOL	increase log verbosity upon encountering an error (default: off)
verbosity	INT	logging verbosity level [0-5] (default: 0)

`[logio]` section - log-based write data storage settings¶
Key	Type	Description
chunk_size	INT	data chunk size (B) (default: 4 MiB)
shmem_size	INT	maximum size (B) of data in shared memory (default: 256 MiB)
spill_size	INT	maximum size (B) of data in spillover file (default: 4 GiB)
spill_dir	STRING	path to spillover data directory

`[margo]` section - margo server NA settings¶
Key	Type	Description
tcp	BOOL	Use TCP for server-to-server rpcs (default: on, turn off to enable libfabric RMA)
client_timeout	INT	timeout in milliseconds for rpcs between client and server (default: 5000)
server_timeout	INT	timeout in milliseconds for rpcs between servers (default: 15000)

`[runstate]` section - server runstate settings¶
Key	Type	Description
dir	STRING	path to directory to contain server-local state

`[server]` section - server settings¶
Key	Type	Description
hostfile	STRING	path to server hostfile
init_timeout	INT	timeout in seconds to wait for servers to be ready for clients (default: 120)
local_extents	BOOL	use server extents to service local reads without consulting file owner

`[sharedfs]` section - server shared files settings¶
Key	Type	Description
dir	STRING	path to directory to contain server shared files

Environment Variables¶

All environment variables take the form UNIFYFS_SECTION_KEY, except for the [unifyfs] section, which uses UNIFYFS_KEY. For example, the setting log.verbosity has a corresponding environment variable named UNIFYFS_LOG_VERBOSITY, while unifyfs.mountpoint corresponds to UNIFYFS_MOUNTPOINT.

Command Line Options¶

For server command line options, we use getopt_long() format. Thus, all command line options have long and short forms. The long form uses --section-key=value, while the short form -<optchar> value, where the short option character is given in the below table.

Note that for configuration options of type BOOL, the value is optional. When not provided, the true value is assumed. If the short form option is used, the value must immediately follow the option character (e.g., -Cyes).

`unifyfsd` command line options¶
LongOpt	ShortOpt
`--unifyfs-cleanup`	`-C`
`--unifyfs-configfile`	`-f`
`--unifyfs-daemonize`	`-D`
`--unifyfs-mountpoint`	`-m`
`--log-verbosity`	`-v`
`--log-file`	`-l`
`--log-dir`	`-L`
`--runstate-dir`	`-R`
`--server-hostfile`	`-H`
`--sharedfs-dir`	`-S`
`--server-init_timeout`	`-t`