Storage Area Networks - Five Nines

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Continuing this week's theme on Storage Area Networks, today I thought I would talkabout the various terms we use for our equipment.

One area of confusion are the adjectives "entry-level", "midrange" and "enterprise-class".What do these mean? Well, as in the case of disk and tape, these three are all relative terms that are a combination of "small, medium, large" as well as "good, better, best".

Entry-Level

Entry-level switches are typically only a maximum of 8-16 ports.Ports can connect the switch to a server, a storage device, or another switch.These are sometimes called "edge" switches, as they might be found in the mostremote sections of an office campus, remote branches, or other isolated areasoutside the primary data center.

Midrange

Midrange switches typically have a maximum of 32-64 ports.More ports on a single switch means fewer switches (and fewer cables) to manage.

Enterprise-Class

These are called "directors" to distinguish them from entry-level and midrange offerings.Directors have a maximum of 140-528 ports, and because so many devices or switches can beconnected to them, they need to be extremely reliable. Directors are designed for 24x7operation, with the ability to make most upgrades and configuration changes while the boxis running (often referred to as "non-disruptive upgrades"). Availability is typically better than "five nines", or 99.999 percent, which means that the box will be up 99.999 percent of the time, or conversely, will be down lessthan 5 minutes per year.

If you are asking yourself "which size is right for my company?" or "is my company big enoughfor a director?" you are asking the wrong questions! Instead, determine a SAN configurationthat meets your workload, and then decide the components for that design.

McData coined a phrase called "core/edge" design that is considered today as "Best Practice" throughout the industry.A good write-up can be found here at SearchStorage.com. Basically, you put your big beefy "core" directors in the center of the room, and then surround it with midrange switches, that then these connect to "edge" switches, that then connect to the servers and storage near them. As you grow, this design can easilyscale to grow with you.

So, if you need help implementing a SAN for the first time, or upgrading the one you have,call IBM, we can help!

technorati tags: IBM, SAN, switches, directors, entry-level, midrange, enterprise, non-disruptive, McData