NOTE: For anyone looking for an actual cost, sorry, there isn’t anything in this blog entry about the actual dollars needed.
I am having a flash back today, it must be the new medication. 🙂
The costs of HA seems to be a normal topic of discussion when a company looks into clustering and has sticker shock. I can’t stress enough that clustering is not the end-all solution. Please do a quick read on my blog about my HA definition.
I was just talking to a client about how much clustering costs and how much the services cost to implement clustering. Yep, it isn’t the same as just installing a standard server and multiplying it times the number of nodes. Servers with large hard drives, lots of RAM and multiple processors have come down a great deal in the last couple of years. What used to be about the cost of a 700 series BMW is now about the cost of a Chrysler 300. Really. However, when you start talking about HA, you have much more than the costs of individual nodes in a cluster.
The main cost issue with clustering is the cost of the additional components that are needed above and beyond the nodes themselves. For example, I keep hearing the term "disk is cheap" bandied (I love that word) about in meetings. It isn’t true in all cases. Yes, a large hard drive is not that expensive. A LUN on a high-end SAN is expensive. It is even more expensive when you consider the initial costs of building the infrastructure to host that LUN.
OK, so back to the discussion of cost. Yes, clustering is costly, because it requires:
- Windows Server 2003, Enterprise Edition which costs a good bit more than Standard Edition
- Host Bus Adapters (two per server for redundancy) for the fiber fabric (yes, there are other less costly alternatives, but let’s stick to mainstream right now) and the software for the HBAs
- Fiber switches
- SAN devices (or NAS depending on the certification of the hardware)
- Experienced administrators (if you want it done right) to design and configure it
- A 24/7 team for maintaining it (remember HA is not just clustering)
- Significant documentation (in case the administrator gets hit by a bus)
- Tried and tested processes
To achieve High Availability, an organization must implement well defiined, planned, tested, and implemented processes, software, and fault tolerant hardware. The focus is application availability. Yes, this costs money.
My favorite sales person used to use this phrase a great deal when we would talk to clients and potential clients about HA, "How much does it cost for the application to be down?" If it doesn’t cost much, implementing clustering and instilling an HA attitude just might now be worth it. If they say it costs a fortune, then the response is simple, "if it costs you so much to be down, why are you sweating this relatively small amount to do the best job possible of keeping it up?"
I hate to think about how many organizations out there are gambling (yep, that is what it is) with their IT assets and the businesses that run on them. If your company will go out of business if an application fails, don’t you owe it to the owners to protect that application?