1LIZARDFS(7) LIZARDFS(7)
2
6 lizardfs, moosefs, mfs - a networking, distributed, highly available
7 file system
8
10 LizardFS is a networking, highly available, distributed file system. It
11 spreads data over several physical localisations (servers), which are
12 visible to a user as one resource. For standard file operations
13 LizardFS acts as other Unix-alike file systems. It has hierarchical
14 structure (directory tree), stores files' attributes (permissions, last
15 access and modification times) as well as makes it possible to create
16 special files (block and character devices, pipes and sockets),
17 symbolic links (file names pointing to another files accessible
18 locally, not necessarily on LizardFS) and hard links (different names
19 of files which refer to the same data on LizardFS). Access to the file
20 system can be limited basing on IP address and/or password.
21 Distinctive features of LizardFS are:
23 • higher reliability (data can be stored in several copies on
25 separate computers)
26 • dynamically expanding disk space by attaching new computers/disks
28 • possibility of storing deleted files for a defined period of time
30 ("trash bin" service on a file system level)
31 • possibility of creating snapshot of a file, which means coherent
33 copy of them whole file, even while the file is being written.
34
36 LizardFS installation consists of five types of machines:
37 • master metadata server (or ‘the master’) a managing server - single
39 computer managing the whole filesystem, storing metadata for every
40 file (information on size, attributes and file localisation(s),
41 including all information about non-regular files, i.e.
42 directories, sockets, pipes and devices.
43 • metadata server shadows (or ‘the shadow’) - almost identical to the
45 master, there can be any number of those, they work as master
46 metadata server backup and they are ready for immediate deployment
47 as new master in case of current master failure.
48 • data servers (any number of commodity servers storing files data
50 and replicating it among themselves (if a certain file is supposed
51 to exist in more than one copy).
52 • metadata backup servers - any number of servers, all of which store
54 metadata changelogs and periodically downloading base metadata
55 file; it’s easy to run mfsmaster process on such machine when
56 primary master stops working.
57 • client computers referring to LizardFS stored files - any number of
59 machines with working mfsmount process that communicates with the
60 managing server to receive and modify file information and with
61 chunkservers to exchange actual file data.
62 Metadata is stored in memory of the managing server and simultaneously
64 is being saved on disk (as a periodically updated binary file and
65 immediately updated incremental logs). The main binary file as well as
66 the logs are replicated to metaloggers (if present).
67 File data is divided to fragments (chunks) of maximum size 64MB each
69 which are stored as files on selected disks on data servers
70 (chunkservers). Each chunk is saved on different computers in a number
71 of copies equal to a "goal" for the given file.
72
74 Report bugs to <contact@lizardfs.org>.
75
77 Copyright 2008-2009 Gemius SA, 2013-2015 Skytechnology sp. z o.o.
78 LizardFS is free software: you can redistribute it and/or modify it
80 under the terms of the GNU General Public License as published by the
81 Free Software Foundation, version 3.
82 LizardFS is distributed in the hope that it will be useful, but WITHOUT
84 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
85 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
86 for more details.
87 You should have received a copy of the GNU General Public License along
89 with LizardFS. If not, see http://www.gnu.org/licenses/.
90
92 mfschunkserver(8), mfsmaster(8), mfsmetalogger(8), mfsmount(1),
93 mfstools(1), lizardfs-admin(8)
94 02/09/2023 LIZARDFS(7)