Even though the upfront costs are likely to be steep, a SAN can actually save you money. Find out if it's the best long-term solution for your storage environment.
When you buy a server, you probably spend a lot of time calculating just how much disk space you'll need for your intended application, both in the present and for the foreseeable future. If you're like most IT pros, you probably make sure your server is well-loaded and ready for anything.
While disk space is relatively cheap, keeping up with everything related to storage -- backing up your data, monitoring usage to keep from running out, upgrading your servers as space runs low, restoring data when disaster strikes or mistakes happen -- can be an expensive proposition. The upfront costs for a storage area network (SAN) can be substantial, but you may be able to save money, both acquisition and management costs, by opting for a SAN. What's more, features found in most SANs might help you avoid disaster -- or at least major inconvenience -- and it's hard to put a price tag on that.
Disk-space wasteland
First off, direct-attached disk space is cheap, so not making the best use of it isn't a huge problem. But, can you guarantee that the space you need will always be on the server on which you need it? You've heard the estate agents' mantra, "Location, location, location". Well, the same holds true in terms of the location of your disk space.
What happens when management drops by your office and says, "Hey there ... we're going to have to ask you to remove the quotas from our inboxes. Thanks." You can shoot back with the reality that your mail server doesn't have enough disk space, but it won't always be well received, especially if you just added a few hundred gigs to the database server.
Alternatively, you might have another server that you overbuilt and that has a ton of available disk space; but that won't do much to resolve your immediate problem.
What if, while your manager was standing right there, you could double the disk space allocated to email with a few clicks of the mouse? That can happen when you use a SAN.
A SAN takes your islands of storage and creates a single pool from which you can draw as necessary. While this upfront disk space is more expensive than the direct-attached variety, the SAN-hosted space can be allocated and monitored much more closely. Now, as you run low on space on a particular volume, you can simply allocate more space from the pool and increase what is provided to that volume.
Disaster recovery
Have you ever had to rebuild a server or even just a single volume of data from backup tapes? Have you ever -- at 5pm -- had to restore a database from the previous night's backup, thus losing all the changes for the current day? If you've been blessed with either of these tasks, you'll know how stressful -- and how expensive -- they can be.
With features found in most SANs, both of these issues can be things of the past, or at least somewhat alleviated. By using snapshots -- point-in-time backups of your data -- you can avoid going to tape for major recovery efforts. Furthermore, you can reduce your window of risk -- the time between backups -- to an hour or two, rather than the typical 24-hour period between backups.
It's always better to be able to recover a database from, say, a 2pm backup, rather than having to go all the way back to before the work day started. And, depending on the criticality of the information, keeping your risk window short could save you a serious amount of money.
Summary
If your need for a SAN is just to save money and you count only the hard costs of disk space and the underlying infrastructure, the SAN investment will not pay off. If, however, you consider staff time and uptime in your calculations, implementing a SAN can be a boon for both you and your users.
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