NAME

       mfsmaster - start, restart or stop Lizard File System metadata server process

SYNOPSIS

       mfsmaster [-f] [-c CFGFILE] [-u] [-d] [-t LOCKTIMEOUT] [ACTION]

       mfsmaster -s [-c CFGFILE]

       mfsmaster -v

       mfsmaster -h

DESCRIPTION

       mfsmaster is the metadata server program of Lizard File System. Depending on parameters it
       can start, restart or stop LizardFS metadata server process. Without any options it starts
       LizardFS metadata server, killing previously run process if lock file exists.

       Metadata server can work in one of two modes (personalities):

        1. master

        2. shadow

       If metadata server works with master personality it acts as main metadata server govering
       all file system metadata modifications. If metadata server works with shadow personality
       it acts as backup metadata server ready for immediate deployment as new master in case of
       current master failure. Shadow only accepts connections from lizardfs-admin, i.e.
       mfschunkserver, mfsmetalogger and mfsmount (the client) are not allowed to connect to
       shadow instance.

       Current metadata server personality is defined in metadata server configuration file and
       can be changed on the fly from shadow to master by proper modification and reloading of
       its configuration file.

       Master and shadow are designed to run simultaneously in sync forever. It is very unlikely
       but still (due to a memory corruption or a bug) possible that after some time their
       metadata will somehow differ. Since version 2.5.2 metadata checksum is maintained both by
       master and shadow, in order to detect and fix possible metadata corruptions. In case
       mismatch is detected shadow asks master to double check its metadata and dump its current
       snapshot. After the metadata is dumped and the checksum in master is recalculated shadow
       downloads the new metadata snapshot, which should ensure that master and all shadows have
       exactly the same metadata.

       SIGHUP (or reload ACTION) forces mfsmaster to reload all configuration files.

       -v
           print version information and exit

       -h
           print usage information and exit

       -f
           (deprecated, use start action instead) forcily run LizardFS master process, without
           trying to kill previous instance (this option allows to run LizardFS master if stale
           PID file exists)

       -s
           (deprecated, use stop action instead) stop LizardFS master process

       -c CFGFILE
           specify alternative path of configuration file (default is mfsmaster.cfg in system
           configuration directory)

       -u
           log undefined configuration values (when default is assumed)

       -d
           run in foreground, don’t daemonize

       -t LOCKTIMEOUT
           how long to wait for lockfile (default is 60 seconds)

       ACTION
           is the one of start, stop, restart, reload, test, isalive or kill. Default action is
           restart.

FILES

       mfsmaster.cfg
           configuration file for LizardFS master process (see mfsmaster.cfg(5) manual)

       mfsexports.cfg
           LizardFS access control file (used with mfsmounts 1.6.0 or later, see
           mfsexports.cfg(5) manual)

       mfstopology.cfg
           Network topology definitions (see mfstopology.cfg(5) manual)

       mfsmaster.lock
           PID file of running LizardFS master process

       .mfsmaster.lock
           lock file of running LizardFS master process (created in data directory)

       metadata.mfs, metadata.mfs.back
           LizardFS filesystem metadata image

       changelog.*.mfs
           LizardFS filesystem metadata change logs (merged into metadata.mfs once per hour)

       data.stats
           LizardFS master charts state

REPORTING BUGS

       Report bugs to <contact@lizardfs.org>.

COPYRIGHT

       Copyright 2008-2009 Gemius SA, 2013-2015 Skytechnology sp. z o.o.

       LizardFS 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 3.

       LizardFS 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 LizardFS. If
       not, see http://www.gnu.org/licenses/.

SEE ALSO

       mfsmetarestore(8), mfschunkserver(8), mfsmount(1), mfsmaster.cfg(5), mfsexports.cfg(5),
       mfstopology.cfg(5), moosefs(7)

                                            01/11/2020                               MFSMASTER(8)