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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
       visible 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 password.

       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
	   machines with working mfsmount process that communicates with the
	   managing 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 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
       mfschunkserver(8), mfsmaster(8),	mfsmetalogger(8), mfsmount(1),
       mfstools(1), lizardfs-admin(8)

				  04/14/2025			   LIZARDFS(7)

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