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MooseFS 3.0.104-1
March 2019
Aliases: mount.moosefs(8)


High performing and fault tolerant distributed file system


mfsmount - mount Moose File System


mfsmount [HOST[:PORT]:[PATH]] [options] mountpoint
mfsmount -h|--help
mfsmount -V|--version
Since 3.0.75 (Linux only):
mount -t moosefs [options] [HOST[:PORT]:[PATH]] mountpoint


Mount Moose File System.
General options:
-h, --help display help and exit
-V display version information and exit
FUSE options:
-d, -o debug
enable debug mode (implies -f)
-f foreground operation
-s disable multi-threaded operation
MooseFS options:
-c CFGFILE, -o mfscfgfile=CFGFILE
loads file with additional mount options
-m, --meta, -o mfsmeta
mount MFSMETA companion filesystem instead of primary MooseFS
-n omit default mount options (-o allow_other)
-p prompt for password (interactive version of -o mfspassword=PASS)
-H HOST, -o mfsmaster=HOST
connect with MooseFS master on HOST (default is mfsmaster)
-P PORT, -o mfsport=PORT
connect with MooseFS master on PORT (default is 9421)
-B IP, -o mfsbind=IP
local address to use for connecting with master instead of default one
-L IP, -o mfsproxy=IP
define listen ip address of local master proxy for communication with tools (default:
-S PATH, -o mfssubfolder=PATH
mount specified MooseFS directory (default is /, i.e. whole filesystem)
-o mfspassword=PASSWORD
authenticate to MooseFS master with PASSWORD
-o mfspassfile=FILENAME
authenticate to MooseFS master with password stored in first line of file pointed by FILENAME
-o mfsmd5pass=MD5
authenticate to MooseFS master using directly given MD5 (only if mfspassword option is not specified)
-o mfsdonotrememberpassword
do not remember password in memory - more secure, but when session is lost then new session is created without password
-o mfsdebug
print some MooseFS-specific debugging information
-o mfsmemlock
try to lock memory (all allocated memory will be mapped to physical RAM - which also means no swapping)
-o allowoomkiller
do not disable out of memory killer (Linux only)
-o mfslimitarenas=N
if N>0 then limit glibc malloc arenas (Linux only - default: 4)
-o mfsflattrash
use flat trash structure in meta (option added for compatibility reasons - since version 3.0.64 trash is split into 4096 subfolders which reduces problems with big trashes)
-o mfsdelayedinit
connection with master is done in background - with this option mount can be run without network (good for being run from fstab / init scripts etc.)
-o mfsmkdircopysgid=N
sgid bit should be copied during mkdir operation (default depends on operating system)
-o mfssugidclearmode=SMODE
set sugid clear mode (see SUGID CLEAR MODES; default depends on operating system)
-o mfscachemode=CMODE
set cache mode (see DATA CACHE MODES; default is AUTO)
-o mfscachefiles
(deprecated) preserve file data in cache (equivalent to ’-o mfscachemode=YES’)
-o mfsattrcacheto=SEC
set attributes cache timeout in seconds (default: 1.0)
-o mfsxattrcacheto=SEC
set extended attributes (xattr) cache timeout in seconds (default: 30.0)
-o mfsentrycacheto=SEC
set file entry cache timeout in seconds (default: 0.0, i.e. no cache)
-o mfsdirentrycacheto=SEC
set directory entry cache timeout in seconds (default: 1.0)
-o mfsnegentrycacheto=SEC
set negative entry cache timeout in seconds (default: 0.0)
-o mfsgroupscacheto=SEC
set supplementary groups cache timeout in seconds (default: 300.0)
-o mfsrlimitnofile=N
try to change limit of simultaneously opened file descriptors on startup (default: 100000)
-o mfsnice=LEVEL
try to change nice level to specified value on startup (default: -19)
-o mfswritecachesize=N
specify write cache size in MiB (in range: 16..2048 - default: 256)
-o mfsreadaheadsize=N
define size of all read ahead buffers in MiB (in range: 16..2048 - default: 256)
-o mfsreadaheadleng=N
define amount of bytes to be additionally read (in range: 128KiB..2MiB - default: 1048576)
-o mfsreadaheadtrigger=N
define amount of bytes read sequentially that turns on read ahead (default: 10 * mfsreadaheadleng)
-o mfsioretries=N
specify number of retiries before I/O error is returned (default: 30)
-o mfstimeout=N
define maximum timeout in seconds before I/O error is returned (default: 0 - which means no timeout)
-o mfslogretry=N
define minimal retry counter on which system will start log I/O messages (default: 5)
-o mfsfsyncmintime=SEC
force fsync before last file close when file was opened/created at least SEC seconds earlier (default: 0.0 - always do fsync before close)
-o mfspreflabels=LABELEXPR
specify preferred labels for choosing chunkservers during I/O
-o mfsnoxattrs
turn off xattr support
-o mfsnoposixlocks
turn off support for global posix locks (lockf + ioctl) - locks will work locally
-o mfsnobsdlocks
turn off support for global BSD locks (flock) - locks will work locally
General mount options (see mount(8) manual):
-o rw|-o ro
Mount file-system in read-write (default) or read-only mode respectively.
-o suid|-o nosuid
Enable or disable suid/sgid attributes to work.
-o dev|-o nodev
Enable or disable character or block special device files interpretation.
-o exec|-o noexec
Allow or disallow execution of binaries.


During attribute change file systems sometimes clear flags suid and/or sgid. Behavior is different on different file systems. MFS tries to mimic behavior of most popular file system on given operating systems.
NEVER MFS will not change suid and sgid bit on chown
ALWAYS clear suid and sgid on every chown - safest operation
OSX standard behavior in OS X and Solaris (chown made by unprivileged user clear suid and sgid)
BSD standard behavior in *BSD systems (like in OSX, but only when something is really changed)
EXT standard behavior in most file systems on Linux (directories not changed, others: suid cleared always, sgid only when group exec bit is set)
XFS standard behavior in XFS on Linux (like EXT but directories are changed by unprivileged users)


There are four cache modes: DIRECT, NO, YES and AUTO. Default option is AUTO and you shuldn’t change it unless you really know what you are doing. In AUTO mode data cache is managed automatically by mfsmaster.
DIRECT forces direct io (bypasses cache)
never allow files data to be kept in cache (safest but can reduce efficiency)
always allow files data to be kept in cache (dangerous)
AUTO file cache is managed by mfsmaster automatically (should be very safe and efficient)


LABELEXPR grammar:
S -> S + M | M
M -> M L | L
L -> a .. z | A .. Z | ( S ) | [ S ]
Subexpressions should be placed in priority order. Up to nine subexpressions (priorities) can be specified.


On most Unix systems mfsmount can be invoked automatically from /etc/fstab. Be aware that rw or ro option has to be specified in options. Also on many systems there should be option which informs the system that this mountpoint should be mounted after starting networking services (options such as _netdev or late).
mfsmount mountpoint fuse options 0 0
mfsmount_magic mountpoint moosefs options,mountprog=/usr/local/bin/mfsmount 0 0
Since version 3.0.75 alternative form can be used:
HOST[:PORT]:[PATH] mountpoint moosefs options 0 0
HOST[:PORT]:[PATH] mountpoint moosefs options,mountprog=/usr/local/bin/mfsmount 0 0


Report bugs to <>.


Copyright (C) 2019 Jakub Kruszona-Zawadzki, Core Technology Sp. z o.o.
This file is part of MooseFS.
MooseFS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2 (only).
MooseFS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with MooseFS; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02111-1301, USA or visit
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