Selecting Products
This week has been spent digging into the details of various SAN and server virtualisation products. It has involved conversations with various vendors. Vendor perspectives were then cross-checked with experiences listed in user forums (love the Web). So much information has been absorbed that it hurts.
Some information has fallen out of the buffer due to capacity limitations. However, the week has been defined by several other frustrations:
- Even after explaining what we want to achieve some vendors were still trying to sell us complex tools that we don’t need. Only one salesperson suggested that their product was not the right tool for a certain requirement.
- Opinions in web forums against using server virtualisation in production environments are strong but rarely backed up with useful facts.
- Even after a week of questions, listening, and research it was realised that we still don’t have enough knowledge to make a truly informed selection.
The first point above is no surprise. However, the latter two are interesting.
Server Virtualisation
The idea of server virtualisation makes some people cringe. It just sounds wrong, but when faced with the prospect of having fifty 1RU servers all doing very little, or five larger servers working harder, it’s difficult to ignore the economics of products like VMware.
While digging around in the VMware forums you see comments like:
- “It’s way slower than just a physical server.”
- “It’s great for dev and test, but I’d never use it for production.”
Details on the basis for these assertions are usually missing. Everyone’s workload profiles, software configurations, and hardware configurations are going to be different so such statements are essentially meaningless.
Sure, a virtualised environment will have overhead. The real question is how that overhead affects your applications in your environment. Even if there might be a 30% networking overhead when using iSCSI to connect to external storage from a Windows virtual machine executing on VMware ESX 3.0 running on a physical server without a TCP/IP Offload Engine (TOE) card, how does that really affect your application when it’s running on a Gigabit Ethernet connection shared by several other virtual machines?
One thing that was obvious this week is that there are opportunities for bottlenecks in virtual server infrastructure, and many of them are nothing to do with the virtualisation layer. e.g. SAN, physical servers, and networking. So how do you decide whether to use a product like VMware?
Making Informed Choices
This week was all about learning more about what current products can do. We needed to validate the physical architecture that we think we need to build. Rather than just ticking off supported features from a check-list, we were also looking at ease of management and alternative ways of meeting our overall business objectives.
Right now the feeling is that we know enough to make a justifiable decision, maybe. The only way to really find out if a product meets our needs is to test it in our own environment, and ensure that it is configured correctly. That takes a lot of time and effort, but the alternatives are to take pot luck or over provision for everything.
If you haven’t got time to evaluate a product in a restricted environment you probably don’t have time to configure and administer it properly in a production environment.