Can virtualisation rejuvenate your old servers?
When should you try the treatment?
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It is a commonly held belief that most servers sit around doing very little most of the time. So, according to the theory, it makes sense to take advantage of that otherwise wasted capacity by loading up a hypervisor and running multiple virtual servers on the same hardware.
If only it were that simple. This kind of server consolidation has its advantages, but it is not necessarily the best or most cost-effective approach to going virtual.
Here’s how to decide for or against.
The first port of call has to be an understanding of what you have and how stretched your hardware really is.
Idle speculation
Guessing isn’t good enough. You may think, for example, that your file-sharing servers sit around idle most of the time, but is that really so or has someone sneaked in a database, a web server or some other CPU-crunching application?
On already maxed-out servers, virtualisation will be a total waste of time, and detailed investigation and measurement is the only sure-fire way of knowing what you are in for.
It is also important to know precisely how each server is configured, and that is where you are most likely to run into the limitations of trying to make do and mend – not least because server technology will, inevitably, have moved on since you bought your kit.
You could easily find your processors unable to support the latest hypervisors, many of which demand on-chip technologies such as Intel VT or AMD-V before they will play ball.
High-class chips
Even where these technologies are available you may need additional processors to cope with virtual machine workloads, and compatible chips can be expensive to source – if, indeed, they are still to be found.
Memory should be easier to locate but can still be costly. Added to which, RAM technology too moves on and you could end up having to buy memory that your older, slower servers can’t fully exploit – the exact opposite of what you want to achieve.
And then there’s the networking side. Multiple virtual machines will need a lot more bandwidth than a single server. Can you get more adapters in? Are the expansion slots fast enough? Will Gigabit cards do or will you need 10GbE, and is that a viable option on the hardware you already have?
Finally there is the little matter of maintenance and support. Keeping your servers up and running becomes even more crucial when hosting multiple virtual machines, and there are limits on how long server vendors will be willing to extend their contracts.
Buying something new may be a better solution
It won’t be cheap, it won’t be easy and, tempting as it may be to think you can get away with consolidating your old hardware, buying something new may be a better solution.
Think about it. Multi-core processors are now commonplace, whereas the average three-year-old server will have single or dual-core CPUs at best.
Cheap thrills
Moreover, with Intel’s Nehalem and the latest AMD Opteron architectures you can expect huge performance gains that enable you to consolidate hundreds of servers onto a minimal number of boxes, at the same time reducing power and cooling overheads.
The latest DDR3 RAM is, similarly, both cheaper and faster than what went before, plus you can now stuff a lot more into the average server.
Add 10GbE, which is rapidly becoming the norm on server motherboards, into the mix and for little more than the cost of upgrading your old hardware, you could buy fewer, newer servers and deliver a great deal more virtualisation bang for your buck. ®
