Friday, January 30, 2009

Redundant Redundancy

Many thanks to Ian Carder for this blog entry!

Over the past year we have replaced all of our remaining Cabletron network equipment with Cisco gear. Being a K-12 School District, we have to be extremely frugal where we spend out money. Often, this comes in direct conflict with going the extra mile to make sure whatever system we're deploying has some redundancy in the event of a failure.

Sometimes I can “sneak” redundancy in without having to pay a hefty price or fight for it. This involves simple things like RAID 1/5/10 on servers, dual power supplies, and dual supervisors in the Cisco core switches. We have been making heavy use of ether channel from MDFs to remote closets. That's a cheap solution assuming you have the available ports and don't feel like you have to over pay for Cisco branded GBICs. The other project we're looking to wrap up is creating more that one route to each building in the district using at least a hub network topology. Sorry, no spokes yet! The benefit here is that if we lose a single building, not all traffic is cut off between buildings on either side of the problem building. Lucky for us, we're all on one LAN, so no shared bandwidth to deal with. Just as with the ether channel situation, as long as you have the cabling between sites and available switch ports, it's a cheap proposition. I also have a small cluster running Novell's Cluster Services, but that was something I had to fight for. Beyond that, everything we have is single tier.

So I pose a couple of questions to the faithful readers; what critical services do you need to make redundant and what on the cheap tricks have you come up with to provide the redundancy?