What is a Storage Area Network?

A Storage Area Network is a way to reliably share hard drive space in a medium to large organization. This sort of data storage requires expensive hardware and was designed to address the needs of a computer data center. These needs came about because sharing and managing large amounts of data, especially if that data is spread around on hundreds of individual PCs, was becoming more difficult. The Storage Area Network, or SAN, solves these problems because all the storage is in one location on the network. By having all the storage in one physical area, it becomes easier to backup the data, it becomes easier to protect the data, and it becomes easier to add more storage. This all adds up to lower costs because the data is easier to manage.

Performance is the primary goal of a SAN. To this end it typically uses the Fibre Channel interconnect and switches. The fastest speeds currently available are 4 Gb/s with 8 Gb/s being just around the corner. To get these kinds of speeds, you need to have a high-end server that can issue overlapping I/Os. In the middle of the SAN reside the switches that route the data traffic between the hosts and the storage devices. Then at the storage device, you have expensive RAID controllers that can handle data streams from multiple hosts. With redundant paths between each host and controller, this performance all adds up to big costs that only a large IT budget can absorb.

Security becomes important when your computers are connected to the Internet and when many people have access to your local network. Two aspects of network security are keeping out unauthorized users and logging all significant activity. Logging is important because it enables an alert administrator to catch an intruder that got past the access controls. Good security can control access to down to small elements in the network such as a single disk. This means that a user my have access to a particular disk in the network without having access to any of the other disks. These and many other features allow SAN to provide robust security for your data.

Scalability is that characteristic of being able to add additional storage without having to pay a disproportional cost for that additional disk space and data transfer performance. An example of a non-scalable system is one where your cost per gigabyte is always increasing as you add more disk storage. In essence, a SAN will allow you to gracefully add more storage capacity.

Manageability has to do with how much effort a System Administrator needs to expend to keep your system running. Typical administrative duties include performing regular backups, adding new users, monitoring security issues, and monitoring performance issues. A Storage Area Network is designed to simplify all of these tasks. There is one system that acts as a gateway to the storage network. This simplifies the task of managing user access lists. The storage controllers can take live snapshots of disks, thereby making regular backups a simple and non-intrusive task. The management stations can provide both live and historical performance data for a single host or the whole system. So by centralizing the storage into a network, management functions are by intrinsic design simplified.

A Storage Area Network is the ideal answer for a growing business that has to manage large amounts of data. Because the SAN data can be backed up while your computers are running, your system will have a higher availability. Which means that your employees will be more productive. Furthermore, because your data is in a central location, rather than being spread about on individual computers, you will find it easier to secure confidential data. This makes it easier to grow your IT infrastructure while your company works on doing what it does best.

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