As Storage Area Networks (SANs) have become increasingly affordable, their use in enterprises and even smaller businesses has become widespread. A SAN carries numerous benefits over direct-attached storage. One significant advantage is that all data on SANs is connected via a network—as opposed to direct-attached storage, in which each individual drive is its own separate entity.
The greatest benefit is scalability. Direct-attached storage is limited by the storage capacity of an individual server. Many iSCSI SANs allow for additional nodes, letting some SANs get into the petabytes for storage capacity. If you're trying to justify a hardware purchase for your organization, having a scalable option allows you to propose a solution based on what you need now, without having to worry as much about what needs you may have in one, three, or five years in the future. Finally, as organizations continue to consolidate with more powerful hardware and greater flexibility via virtualization, using a scalable device such as a SAN makes sense.
However, despite the compelling proposition that SANs offer for enterprise storage, iSCSI SANs didn't rise to prominence until a few years ago, with the increased performance of Ethernet networks and reduced costs. Today, iSCSI SANs are an excellent storage choice for most companies, combining the ease of use that simpler storage methods (direct-attached storage) offer with many of the performance and capability gains you'd get with the more expensive Fiber Channel SAN. The biggest drawback to a Fiber Channel SAN is implementation cost and complexity, but Fiber Channel SANs are generally considered to offer faster performance. (Do note, however, that an iSCSI SAN that supports 10GbE might actually be faster than a Fiber Channel SAN.) Other concerns exist as well, such as the limited range of Fiber Channel SANs and the higher maintenance costs.
Some organizations prefer network-attached storage (NAS) over SAN because a NAS is easier to deploy and generally comes at a lower cost. However many SANs can also function as an NAS, which offers both ease of deployment and scalability. To learn more about this topic, read "SAN and NAS: Better Together" at www.windowsitpro.com, InstantDoc ID 39189.
Factors to Consider
In the table on the following pages, you'll note the following major distinctions between leading iSCSI SANs. Which product is best for your company will depend on your needs.
Cost. In the table, SAN costs range from a few thousand dollars all the way to $1 million when fully equipped. As with all purchasing decisions, you have to weigh the features most important to your company against budget constraints. (Note, however, that these are list prices and may not reflect the final price a vendor will give you.)
Features. If features such as thin provisioning, replication, and Fiber Channel support are important for your implementation, you'll most likely want to consider one of the higher-end iSCSI SANs. Thin provisioning means greater storage efficiency (don't need unused storage) and replication enhances data collaboration and can simplify data recovery.
Storage capacity. If the features listed above aren't key driving factors, then one of your top priorities will be storage space for your needs. Total capacity ranges across the products in the table from 100TB–3,000TB. Some SANs can also accommodate additional nodes which increases storage flexibility.
Missing from this Buyer's Guide are several key vendors, including Dell, Oracle, EMC, and IBM. I've tried contacting these vendors but have been unable to obtain information about their products to add. Also, some vendors aren't included in this Buyer's Guide because their products are low-end SANs, targeted at small businesses. Consider reading last year's iSCSI SAN Buyer's Guide for low-end products under $10,000.
Additionally, one of the vendors in the table, QSAN Technology, came back to me recently and it turns out the company has several more iSCSI SANs. I wasn't able to get them into the table, but please visit the company's website for further details.
Are you sold on iSCSI SANs? If so, I encourage you to look through the Buyer's Guide table for the product that is best for your needs. If you're not to that point yet, I recommend additional reading, such as "NAS vs. SAN," to help determine the best solution.