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As you’re no doubt aware, computer storage has come a long way in the past 10 years. Gone are the days when you could run your Windows PC on a 42MB hard disk and when a 210MB drive used to cost $980. Capacity is not so much an issue these days, as gigabytes are relatively cheap. On top of the list now is availability, performance and manageability. There are a number of solutions to these problems, of which Storage Area Networks are but one.

In this article I’ll attempt to give you a brief introduction to what is one of the IT industries newest and hottest technologies, from a perspective that an Overclocker can understand. There are bigger and better storage systems than you’ll see here, and if you have them at work, how about offering me a job? :)

The Storage Conundrum: An Overclockers View
As PC enthusiasts there are a few points we are all concerned with when it comes to storage. This is a list of the main ones:

• Capacity – Put simply, Gigabytes. And the ability to add more of them as needed. Generally more is better. Though sheer size can have a detrimental impact on other areas.
• Performance – The biggest hard drive in the world is of limited value if it takes forever to read the data on it.
• Availability – Keeping your data online and accessible. For most of us that means making sure that Counter-Strike will still load if a drive crashes.
• Backups – The ability to recover data that has been lost due to a failure. Wouldn’t you hate to lose those pr0n…. I mean Map Packs you spent hours downloading?
• Noise and Cooling – Modern drives generally increase performance by increasing the RPM’s that the drives spin at. This can lead to increased noise, as well as large heat output. Even if you have room for a lot of drives in your case, can you handle the noise? Especially after you add half a dozen 120mm cooling fans to the side of your PC.

So what’s the solution to an Overclockers storage problems? Well, let’s imagine for a moment that you’ve just won lotto.

Enter the SAN: Utopian Storage for the Disgustingly Wealthy
So what is a Storage Area Network? In simple terms, it’s not much different to the standard Local Area Network (LAN) that we’re all familiar with. There are still network cards, switches, hubs and cables. However instead of networking machines using TCP/IP over Ethernet, we’re networking hard drives using SCSI over Fibre Channel.

Fibre Channel is used rather than Ethernet as it has characteristics that are suited to SCSI and storage. It’s beyond the scope of this article to go into the differences but I came across an analogy that will put it into perspective: Imagine you have a file that is represented by a stack of 500 sheets of paper. With Fibre Channel I would simply hand you the stack. Using TCP/IP I give you the stack, one sheet at a time.

Incidentally you can run TCP/IP LAN traffic over Fibre Channel too if you wish. It’s really only of benefit to those whose traffic loads cause Ethernet to buckle under the collision load or require Quality of Service/Guaranteed bandwidth functions.

As with any exotic technology, Fibre Channel gear isn’t cheap. While you can buy a Gigabit network card for a couple of hundred dollars, a Gigabit Fibre Channel Host Bus Adaptor will set you back several thousand. You don’t even want to know what a 16 port Fibre Channel Switch is worth. But hey, we’ve just won lotto right?

Hardcore Storage for the Overclocker: Compaq’s EMA12000
This is Compaq’s Enterprise Modular Array, one of two units that we have at my current place of employment. These two units support around 20 servers, servicing approximately 700 users.

click to enlarge - the whole system

Capacity? No problem. We’ve got room for 72 x 72GB drives (using dual-redundant RAID controllers) for over 5 terabytes (5000GB) of disk space.

click to enlarge - hot-swappable disk

So, besides all the HDD's, what else is in the rack?

NEXT PAGE - The System in Detail

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