lizardfs, moosefs, mfs - a networking, distributed, highly available file system
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
•possibility of creating snapshot of a
file, which means coherent copy of them whole file, even while the file is
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
•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.
Report bugs to <email@example.com>.
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/.
mfschunkserver(8), mfsmaster(8), mfsmetalogger(8), mfsmount(1), mfstools(1),