Click here to download this month's buyer's guide chart as an Excel file.

You've probably noticed that your storage needs increase every day. Between email, databases, and applications, businesses of all sizes simply need to store more today than ever before. Luckily, storage prices continue to fall dramatically, so it's possible to keep up.

In businesses of all sizes, but especially small-to-midsized businesses (SMBs), iSCSI SANs gain more popularity every year, thanks in large part to their affordable prices. Entry-level iSCSI SANs are one of the fastest-growing areas, with these less-expensive options increasingly including features such as snapshotting and replication that were available only on high-end SANs in the past.

This month's buyer's guide table will give you an overview of the market. You'll see that the range of iSCSI options is huge, with some products priced at over $40,000 and some under $1,500, so make sure to consider your options carefully. Just as it's a big decision to go with iSCSI over alternative technologies, the level of iSCSI solution you decide to buy will have a big impact on how well it works for your environment.

iSCSI vs. DAS and Fibre Channel
DAS can be simpler than a SAN, especially at first, but DAS setups are limited by the amount of storage that can be attached to a single host. As you add more DAS storage, you have to deal with the infrastructure headaches that come from juggling the storage attached to separate servers. Multi-platform environments are another challenge for DAS—you have to make sure the Macs and Linux machines can share storage with your Windows machines.

Fibre Channel (FC) still offers better performance than iSCSI, but you'll definitely pay for that performance. FC has high implementation and support costs that tend to make it unpopular with SMBs. It's worth noting that while FC is still generally faster, the question of performance between iSCSI and FC isn't perfectly clear-cut. A few entries in our list support 10Gb Ethernet, so iSCSI could get close to FC speeds, and the iSCSI protocol could actually give a slight speed advantage for certain workloads with small, block random I/O, such as virtualization.

iSCSI is something of a compromise compared to DAS and FC storage. DAS might be easier than iSCSI for relatively small amounts of data, but it's hard to scale up. FC provides the same kind of consolidated storage as iSCSI and will usually provide better performance, but costs more and has more complex hardware requirements. iSCSI hits a spot in between, being relatively inexpensive and providing good performance.

What You Need
There are plenty of factors to consider when choosing an iSCSI SAN. Some are obvious, but a few are tricky. Disk capacity is probably the simplest factor to take into account. Today's disk capacities would have seemed ridiculous just a few years ago—terabyte consumer-grade hard drives are now available for under $100, so it's no surprise that at the high end, iSCSI SANs are available with base capacities approaching 100TB and maximum capacities of half a petabyte.

Don't be shortsighted when you're choosing how much storage to buy, but you don't have to be excessive either. One advantage of going with an iSCSI SAN is that you can add storage later. Be sure to check how scalable a SAN is before you buy it, because you could be able to defer some of your storage costs until you actually need the space.

Performance is also an important factor to consider. Not all iSCSI SANs support Serial Attached SCSI (SAS) drives, which are generally more expensive but faster than Serial ATA (SATA) drives. Some offer FC support, and a few have 10Gb Ethernet support.

The buyer's guide table addresses many of the factors you should consider when choosing an iSCSI SAN, but remember to take into account the unique factors of your business. Power consumption is a factor for some companies. Hot swapping or adding drives could be more important for others. Your usage habits are unique, so fully understand what you need before you take the leap.

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