Obviously, I’m not referring to the “BestBuy” version of computers we all tend to have in our own homes. I’m referring to servers built on the either the 64-bit x86 processors from AMD or Intel. Forgive me, as I tend to get a little agitated when people attempt to define “Mission Critical” from a perspective of server hardware. To me, doing so is utter nonsense, since it’s really how the hardware is used that defines whether it’s part of a “Mission Critical” (or “Business Critical”) solution or not.
There are plenty of people out there, using hardware that the hardware vendors have not classified as “Mission Critical”, for what amounts to being highly “mission critical” solutions for their businesses, and vice versa (people using servers that are “mission-critical” for workloads that really aren’t). Examples of this use could include mail servers, firewalls, small but critical databases, etc, etc. There are also examples that are time dependent in nature; For instance, what would happen if a file and print service that was being used by the finance department to generate various time sensitive reports went off-line during the end of quarter or year processing…?
I know, it’s a contrived example, but it does actually demonstrate the point. It is how a given system is used within the business that defines its degree of criticality, not the server it runs on!
I’ll be the first to concede that hardware certainly can help ensure that a mission critical service/workload remains available to its end users (and can, sometimes, be very good at ensuring the service/workload is not available too!) but it’s by no means the only or most critical component in that equation!
What defines “availability”?
To some, the “number of nines” – i.e. “five nines” means 99.999% availability – is the gold standard. I tend to agree that the “number of nines” is certainly not only one of the best known metrics for availability, it’s also a very good one. It captures the essence of the problem; How much time did my service spend being available to its consumers versus the amount of time it was unavailable. And a typical “Mission Critical” environment tends to operate within the 4-5 “nines” range.
Since “four nines” represents about 52 minutes of downtime, and “five nines” about 5 minutes of downtime per year, most people tend to only think in terms of large, expensive, “enterprise class” servers when thinking about architecting for mission critical workloads. Why? Because, historically speaking, these systems were the only ones where it was technologically feasible to include the level of silicon and hardware designs containing the capabilities needed in order to guarantee four or five nines at a price point customers (you) were willing to accept.
However, with the growing acceptance of virtualization technologies such as VM Ware, Microsoft hyper B., Citrix and server and the various open source virtualization technologies included in the major commercial Linux distributions, the picture of what a “mission-critical” server looks like has changed.
It’s now possible to quickly build “always on” system architectures based on industry-standard hardware and extremely flexible hypervisor’s and management software. And you can do it for what amounts to pennies on the dollar compared to the traditionally very expensive and often proprietary systems from the likes of Bull, Fujitsu, NEC, IBM, Sun (now Oracle), HP, etc.
In my view, the greatest paradigm shift in terms of highly available mission-critical workload designs, follows on the heels of one key enabling technology. The advent and acceptance of live-migration in production environments, basically means that there are no technological limits to how flexible your application environment can be. If you were to pair “always-on” live migration, resource management, high availability services, data replication and a little bit of ingenuity, you could with relative ease have a fault tolerant solution for your application environment. Or, if your resource needs aren’t too great, you could leverage the VMware ESX 4.0 fault tolerance capability. Basically the sky’s the limit!
So, to answer my first question, yes PCs can be used for mission-critical workloads. The introduction of virtualization technologies to the x86 platform only makes your job of ensuring availability for those mission-critical workloads a whole lot easier. At least, that’s my opinion.
Good brief and this mail helped me alot in my college assignement. Thank you as your information.