Editing GFS2 (section)

== Hardware ==

The design of GFS and of GFS2 targets [[storage area network]] (SAN)-like environments. Although it is possible to use them as a single node filesystem, the full feature-set requires a SAN. This can take the form of [[iSCSI]], [[Fibre Channel]], [[ATA over Ethernet]] (AoE), or any other device which can be presented under [[Linux]] as a block device shared by a number of nodes, for example a [[DRBD]] device.

The [[distributed lock manager]] (DLM) requires an [[Internet Protocol|IP]] based network over which to communicate. This is normally just [[Ethernet]], but again, there are many other possible solutions. Depending upon the choice of SAN, it may be possible to combine this, but normal practice{{Citation needed|date=July 2010}} involves separate networks for the DLM and storage.

The GFS requires a [[fencing (computing)|fencing]] mechanism of some kind. This is a requirement of the cluster infrastructure, rather than GFS/GFS2 itself, but it is required for all multi-node clusters. The usual options include power switches and remote access controllers (e.g. [[Dell DRAC|DRAC]], [[Intelligent Platform Management Interface|IPMI]], or [[HP Integrated Lights-Out|ILO]]). Virtual and hypervisor-based fencing mechanisms can also be used. [[Fencing (computing)|Fencing]] is used to ensure that a node which the cluster believes to be failed cannot suddenly start working again while another node is recovering the journal for the failed node. It can also optionally restart the failed node automatically once the recovery is complete.