For years, centralized storage meant complex Fiber Channel Storage Area Networks (FC SAN) which were very expensive. Large enterprises were prepared to pay big premiums for such centralized storage networks, as storing valuable data scattered over hundreds of servers would cost them a lot more. The risk of losing data was higher, and decentralized storage resulted in a lot more work for the system administrators. As the necessary storage capacity doubled and still doubles every 18 months, scalability not simplicity was the priority. Hence, the expensive but scalable SANs paid for themselves over time by making the datacenter easier to maintain with fewer people and lower data loss risks.

However, for an SME (Small/Medium sized Enterprise), SANs were simply overpriced storage arrays. The SME has fewer servers that need access to shared storage, so complex switching fabrics with routing are usually unnecessary. The need for less storage capacity and more simplicity doesn't mean that centralized storage capacity cannot be a huge advantage for some SMEs. SMEs that offer web services are especially interested in an affordable form of centralized storage.

We have been working with quite a few SMEs the past several years, and making storage more scalable is a bonus for those companies. However, it is not the main reason companies are looking into SANs. If your company depends on a web service, you want your server to be available around the clock. That means that you will almost certainly be looking towards clustering and failover techniques. These High Availability (HA) technologies - whether on a virtual (VMware HA, Xen HA) or a physical server - in many cases require a shared storage device to work well.

HA together with making storage easier to maintain are the two main reasons why affordable shared storage is desirable, even in an environment where only a few servers are necessary. VMware's Vmotion is another reason why the interest for centralized storage is increasing. Vmotion is not really an alternative for the traditional failover and HA technologies, but it allows for hardware maintenance and server migration from one machine to another without any downtime. In order to make this work, you also need shared storage.

The SME's renewed interest for centralized storage has drawn the attention of the big storage vendors. Since 2006, HP, Netapp, Sun, IBM, Fujitsu-Siemens, and EMC have all launched quite a few product lines targeted at the SME. Many of these "SME products" start at a relatively low price, but a complete storage solution can still carry a very hefty price tag. It is not surprising that the SME product lines are in fact somewhat downsized high-end solutions if you consider that the SME market (about $1 billion) is probably only a small fraction of the $17 billion storage market (See IDC's 2006 report).

Anyway, the idea behind this article is not to discuss the technology and business trends in the professional IT market. There are enough articles covering that. As part of a larger project of helping the SMEs with their datacenter choices, we will try to find out which solutions offer good price/performance without omitting any critical features. If you are relatively new to storage, we'll give you a crash course.
Storage Crash Course...
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  • microAmp - Wednesday, November 7, 2007 - link

    I was just about to post something similar. <thumbsup>

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