Both fibrechannel (FC) and iscsi are made to serve two main purposes
- Provide machines the illusion of local storage when in fact they are using network or remote storage.
- Allow multiple machines to access a common storage target.
Protocols such as these are the backbone of modern Storage Area Networks (SAN).
Fibre Channel
Fibre Channel can be broken into two categories.
- The traditional FC that utilizes a proprietary protocol with fiber based physical networking.
- Fibre channel requires special Host Bus Adapters (HBA) and special switching devices that support the specific protocol.
- Fibre Channel over Ethernet (FCoE) uses the same protocol as traditional fibre channel, but encapsulates the traffic such that it can be transferred over existing networking topologies.
FOOBAR INC uses fibre channel in 2 locations.
- The production storage backbone for our vmware cluster. It consists of a single 8port Qlogic FC switch sharing 2 datastorage devices with 4 vmware hypervisors. See vmware for more detatils on the vmware config.
- The shared storage for all of our clusters is backed by FC. For the setup configureation see cluster-san
iSCSI
Like FC iSCSI allows for systems to treat network based storage as if it were local. This is accomplished by a service intercepting any SCSI (hard disk) commands that would be sent to storage. A client (iSCSI initiator) encapsulates the SCSI commands in a network packet, and sends them to the machine that physically contains the storage (iSCSI target). This can all be done via normal ethernet devices, but for best performance specialized adapters are recommended.
FOOBAR INC used to use iSCSI for much of its VMware storage, but in 2010 this was replaced with Fibre Channel. Although iSCSI worked as expected, it did not provide us with the speed and stability that Fibre Channel could.