Global file system
| Developer(s) | Red Hat |
|---|---|
| Full name | Global File System 2 |
| Introduced | 2005 with Linux 2.6.19 |
| Structures | |
| Directory contents | Hashed (small directories stuffed into inode) |
| File allocation | bitmap (resource groups) |
| Bad blocks | No |
| Limits | |
| Max. number of files | Variable |
| Max. filename length | 255 bytes |
| Allowed characters in filenames | All except NULL |
| Features | |
| Dates recorded | attribute modification (ctime), modification (mtime), access (atime) |
| Date resolution | Nanosecond |
| Attributes | No-atime, journaled data (regular files only), inherit journaled data (directories only), synchronous-write, append-only, immutable, exhash (dirs only, read only) |
| File system permissions | Unix permissions, ACLs and arbitrary security attributes |
| Transparent compression | No |
| Transparent encryption | No |
| Data deduplication | across nodes only |
| Other | |
| Supported operating systems | Linux |
| Developer(s) | Red Hat (formerly, Sistina Software) |
|---|---|
| Full name | Global File System |
| Introduced | 1996 with IRIX (1996), Linux (1997) |
| Structures | |
| Directory contents | Hashed (small directories stuffed into inode) |
| File allocation | bitmap (resource groups) |
| Bad blocks | No |
| Limits | |
| Max. number of files | Variable |
| Max. filename length | 255 bytes |
| Allowed characters in filenames | All except NULL |
| Features | |
| Dates recorded | attribute modification (ctime), modification (mtime), access (atime) |
| Date resolution | 1s |
| Attributes | No-atime, journaled data (regular files only), inherit journaled data (directories only), synchronous-write, append-only, immutable, exhash (dirs only, read only) |
| File system permissions | Unix permissions, ACLs |
| Transparent compression | No |
| Transparent encryption | No |
| Data deduplication | across nodes only |
| Other | |
| Supported operating systems | IRIX (now obsolete), FreeBSD (now obsolete), Linux |
In computing, the Global File System 2 or GFS2 is a shared-disk file system for Linux computer clusters. GFS2 differs from distributed file systems (such as AFS, Coda, InterMezzo, or GlusterFS) because GFS2 allows all nodes to have direct concurrent access to the same shared block storage. In addition, GFS or GFS2 can also be used as a local filesystem.
GFS has no disconnected operating-mode, and no client or server roles. All nodes in a GFS cluster function as peers. Using GFS in a cluster requires hardware to allow access to the shared storage, and a lock manager to control access to the storage. The lock manager operates as a separate module: thus GFS and GFS2 can use the Distributed Lock Manager (DLM) for cluster configurations and the "nolock" lock manager for local filesystems. Older versions of GFS also support GULM, a server-based lock manager which implements redundancy via failover.
GFS and GFS2 are free software, distributed under the terms of the GNU General Public License.
Development of GFS began in 1995 and was originally developed by University of Minnesota professor Matthew O'Keefe and a group of students. It was originally written for SGI's IRIX operating system, but in 1998 it was ported to Linux since the open source code provided a more convenient development platform. In late 1999/early 2000 it made its way to Sistina Software, where it lived for a time as an open-source project. In 2001, Sistina made the choice to make GFS a proprietary product.
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