Moose File System
|Stable release||1.6.27-5  / February 10, 2014|
|Operating system||Linux, FreeBSD, Solaris, OpenSolaris, Mac OS X|
|Type||Distributed file system|
|License||GNU General Public License v3|
Moose File System (MooseFS) is a distributed file system developed by Gemius SA. The lead developer is Jakub Kruszona-Zawadzki. MooseFS aims to be fault-tolerant, scalable general-purpose file system for data centers. Initially proprietary code, it was released to the public as open source on May 5, 2008.
- Metadata server (MDS) — manages the location (layout) of files, file access and namespace hierarchy. The current (1.6.27-5) version of MooseFS does not support multiple metadata servers nor failover. Clients only talk to the MDS to retrieve/update a file's layout and attributes; the data itself is transferred directly between clients and chunk servers. The Metadata server is a user-space daemon; the metadata is kept in memory and lazily stored on local disk.
- Metalogger server — periodically pulls the metadata from the MDS to store it for backup. Since version 1.6.5, this is an optional feature. Eventually[when?] it will be possible to turn the metalogger server into a failover MDS by using the Common Address Redundancy Protocol.
- Chunk servers (CSS) — store the data and optionally replicate it among themselves. There can be many of them, though the scalability limit has not been published. The biggest cluster reported so far consists of 75 servers. The Chunk server is also a user-space daemon that relies on the underlying local file system to manage the actual storage.
- Clients — talk to both the MDS and CSS. MooseFS clients mount the file system into user-space via FUSE.
To achieve high reliability and performance MooseFS offers the following features:
- Fault-tolerance — MooseFS uses replication, data can be replicated across chunkservers, the replication ratio (N) is set per file/directory. If (N-1) replicas fail the data will still be available. At the moment MooseFS does not offer any other technique for fault-tolerance. Fault-tolerance for very big files thus requires vast amount of space - N*filesize instead of filesize+(N*stripesize) as would be the case for RAID 4, RAID 5 or RAID 6.
- Striping — large files are divided into chunks (up to 64 megabytes) that might be stored on different chunk servers in order to achieve higher aggregate bandwidth.
- Load balancing — MooseFS attempts to use storage resources equally, the current algorithm seems to take into account only the consumed space.
- Security — Apart from classical POSIX file permissions, since the 1.6 release MooseFS offers a simple, NFS-like, authentication/authorization.
Hardware, software and networking
- Distributed file system
- List of file systems, the distributed fault-tolerant file system section