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LIZARDFS(7)							     LIZARDFS(7)

NAME
     lizardfs,	moosefs,  mfs - a networking, distributed, highly available file
     system

DESCRIPTION
     LizardFS is a networking, highly available,  distributed  file  system.  It
     spreads data over several physical localisations (servers), which are visi-
     ble  to  a user as one resource. For standard file operations LizardFS acts
     as other Unix-alike file systems. It has hierarchical structure  (directory
     tree),  stores files' attributes (permissions, last access and modification
     times) as well as makes it possible to  create  special  files  (block  and
     character	devices, pipes and sockets), symbolic links (file names pointing
     to another files accessible locally, not necessarily on LizardFS) and  hard
     links  (different names of files which refer to the same data on LizardFS).
     Access to the file system can be limited basing on IP address and/or  pass-
     word.

     Distinctive features of LizardFS are:

     *	 higher  reliability  (data  can be stored in several copies on separate
	 computers)

     *	 dynamically expanding disk space by attaching new computers/disks

     *	 possibility of storing deleted files  for  a  defined	period	of  time
	 ("trash bin" service on a file system level)

     *	 possibility  of  creating snapshot of a file, which means coherent copy
	 of them whole file, even while the file is being written.

ARCHITECTURE
     LizardFS installation consists of five types of machines:

     *	 master metadata server (or `the master') a  managing  server  -  single
	 computer managing the whole filesystem, storing metadata for every file
	 (information  on  size,  attributes and file localisation(s), including
	 all information about non-regular  files,  i.e.  directories,	sockets,
	 pipes and devices.

     *	 metadata  server  shadows  (or  `the shadow') - almost identical to the
	 master, there can be any number of those, they work as master	metadata
	 server backup and they are ready for immediate deployment as new master
	 in case of current master failure.

     *	 data  servers	(any  number of commodity servers storing files data and
	 replicating it among themselves (if a certain file is supposed to exist
	 in more than one copy).

     *	 metadata backup servers - any number of servers,  all	of  which  store
	 metadata  changelogs  and  periodically downloading base metadata file;
	 it's easy to run mfsmaster process on such machine when primary  master
	 stops working.

     *	 client computers referring to LizardFS stored files - any number of ma-
	 chines  with working mfsmount process that communicates with the manag-
	 ing server to receive and modify file information and with chunkservers
	 to exchange actual file data.

     Metadata is stored in memory of the managing server and  simultaneously  is
     being  saved on disk (as a periodically updated binary file and immediately
     updated incremental logs). The main binary file as well  as  the  logs  are
     replicated to metaloggers (if present).

     File  data is divided to fragments (chunks) of maximum size 64MB each which
     are stored as files on selected disks on data servers (chunkservers).  Each
     chunk  is	saved  on  different  computers in a number of copies equal to a
     "goal" for the given file.

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 Soft-
     ware 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 de-
     tails.

     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
     mfschunkserver(8),   mfsmaster(8),   mfsmetalogger(8),   mfsmount(1),  mfs-
     tools(1), lizardfs-admin(8)

				   08/30/2026			     LIZARDFS(7)

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