Cloud computing

(this post will also appear in our virtual private server blog)

Ok, this had to come. Sooner or later – cloud computing. In a nutshell, do we offer it: yes – if the very specific advantages of the cloud warrant its use.

So, what is it – why are so many people crazy about it, and why is it so expensive, compared to a virtual private server or dedicated servers? Essentially, it is simply a different concept of providing resources on demand that can seemingly scale ad infinitum, with similar contention disadvantages like a virtual private server, however. Why? Because eventually, also cloud resources must run on a physical machine. And typically, you won’t be the only person using this machine for your cloud purposes, hence you share the resources with others, and therefore there will always be a level of contention subject to the ISP’s discretion – even if you use very sophisticated virtualisation and isolation methods. Most ISPs sell you cloud computing as a hype, when in fact it is very little else than a different version of a virtual private server.

Of course, cloud crusaders will tell you why you must have a cloud, and start explaining about the additional layer of flexibility, redundancy, security, scalability, etc. In return, one can ask questions such as: do you really want to host your confidential and secure data in a cloud without being able really pinpoint the exact location? Your data is “somewhere in the cloud”. How secure does that make you feel? How redundant is it really? How can I determine redundancy if it is not even clear to me where exactly my data is stored? What different level of redundancy is there compared to normal Raid systems and backup/recover solutions? My application’s resource usage varies by 25% only, why can I not go for a dedicated setup instead, or a virtual private server even?

We still consider one of the cloud’s main advantage its flexibility for sites and application that vary a lot in their resource use over time, with very irregular patterns as well. While they can scale a lot (depending on what you agree upon with your ISP), there will still be resource limits to be observed, so even in a cloud you should take care of estimating your expected peak resource usage.

This is a very basic and by no means comprehensive statement – there are a lot more complex issues to be observed with clouds – put the other way round: normally, even for very complex and high resource applications, you will only need a cloud if you can state its technical advantages over a virtual private server / VPS and dedicated server. Otherwise, in 99 out of 100 cases you will be better of with the latter, outside the cloud.

A very good read is http://www.eucalyptus.com/resources/info/cloud-myths-dispelled – 4 important technical aspects when it comes to cloud computing.

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