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.
[3] It was originally written for SGI's IRIX operating system, but in 1998 it was ported to Linux (2.4)[4] since the open source code provided a more convenient development platform.
Developers forked OpenGFS from the last public release of GFS and then further enhanced it to include updates allowing it to work with OpenDLM.
But OpenGFS and OpenDLM became defunct, since Red Hat purchased Sistina in December 2003 and released GFS and many cluster-infrastructure pieces under the GPL in late June 2004.
Red Hat Enterprise Linux 5.2 included GFS2 as a kernel module for evaluation purposes.
As of Red Hat Enterprise Linux 8.3, GFS2 is supported in cloud computing environments in which shared storage devices are available.
[7] The following list summarizes some version numbers and major features introduced: The design of GFS and of GFS2 targets storage area network (SAN)-like environments.
Depending upon the choice of SAN, it may be possible to combine this, but normal practice[citation needed] involves separate networks for the DLM and storage.
The usual options include power switches and remote access controllers (e.g. DRAC, IPMI, or ILO).
Some of these are due to the existing filesystem interfaces not allowing the passing of information relating to the cluster.
When in EX mode, an inode is allowed to cache data and metadata (which might be "dirty", i.e. waiting for write back to the filesystem).
Of course, doing these operations from multiple nodes will work as expected, but due to the requirement to flush caches frequently, it will not be very efficient.
Here is a summary of those features not already mentioned in the boxes to the right of this page: GFS2 was designed so that upgrading from GFS would be a simple procedure.
Some spare blocks in the GFS journals are used to create the (very small) per_node files required by GFS2 during the update process.