Storage Area Networks – N10-008 CompTIA Network+ : 1.7

Storage area networks allow access to vast amounts of data across the network. In this video, you’ll learn about SANs, including Fibre Channel, Fibre Channel over Ethernet, and iSCSI.

As a network administrator, you’ll be asked to connect many different kinds of storage systems to your network. One of these systems might be a Storage Area Network, or a SAN. To the users, a SAN appears like a local drive. So it acts– it works very similar to a hard drive or an SSD that you might have in your system.

A SAN generally operates as block-level access. This means that if you have a very large file, and you only need to change one small piece inside of that file, you don’t have to overwrite the entire file to the SAN. Instead, you would only change the small block inside of that file to be able to make that change. That means it’s very efficient when you’re reading or writing information from a SAN.

But of course, unlike the local hard drive or SSD that may be in your local computer, you have to access this SAN across the network. This means there will be additional network bandwidth required, and it’s not unusual to see a SAN that would have its own dedicated network, so that you have the best possible throughput to the SAN.

Another common high-speed storage technology is Fibre Channel, or FC. This allows you to connect servers and storage together in a very high-speed network. And it’s very common to see 2, 4, 8, and 16 gigabit per second rates on a Fibre Channel network. Although we call this Fibre Channel, this actually can operate, not only over fiber optics, but there are copper options as well.

To be able to use Fibre Channel, you would need a Fibre Channel switch. You would normally connect your servers, or what Fibre Channel calls an initiator, to the Fibre Channel interface on the switch. You would then connect to the storage system, called the target, using some well-known type of connectivity.

This means that we would, commonly, use SCSI commands, serial-attached SCSI, or SATA commands to be able to access those storage devices. This means from the perspective of the end user. these are locally connected drives, very similar to the experience you get when using a SAN.

Of course, not all of your servers are going to have Fibre Channel interfaces and connect directly to a Fibre Channel switch. But you can use Fibre Channel over Ethernet, or FCoE. This means you wouldn’t need any special hardware to connect these devices to the Fibre Channel network, but you probably are integrating with an existing Fibre Channel infrastructure. This is a switch technology, which means the Fibre Channel over ethernet is running within a single broadcast domain and is not sending routable information.

And another type of storage architecture is iSCSI. This is the Internet Small Computer Systems Interface. You may already be familiar with SCSI drives that we’ve had in our servers for many years, where now we’re able to network that communication using iSCSI. This is a standard created by IBM and Cisco, and it’s now part of an RFC.

Similar to Fibre Channel, an iSCSI drive looks and acts as if it is a local drive on your system. This means that we can manage it very well in the software that we’re using. And there are drivers available for iSCSI connectivity and almost every operating system.