As you probably already know, up to this point the CPU power of our VPS shares was a pretty linear thing: two shares provided exactly twice as much power as one, and this ratio went all the way up to 24 shares.
We placed a CPU limit on how much a single share could use, but the downside of this was that heavy applications such as Wordpress or Joomla required at least two shares to run well. We wanted to change this to make better use of resources and give you more power.
We have therefore decided to round up the burst CPU power provided with your shares to the nearest core: so beginning with one share, you have a full core for your server. At 5 shares, you go to two cores, etc. up to 24 shares (6 cores).
Since we can migrate your VPS from one physical machine to another on demand we can keep a fair balance between the CPU usage across the machine which roughly handles60 shares, or about 40 servers per physical machine.
The bandwidth available to your server is still increased by a rate of 5Mb/s per share as you increase the number of shares you have. Increasing the number of shares is therefore still necessary if your website generates a significant amount of traffic, however you can stick with a single share if you only need your server for a simple blog without much need for bandwidth. This is because the burst CPU power is much higher.
So as a result of these changes:
- 1 share is now much more powerful with the new structure (we have carried out benchmarks that show this, and I will let you try for yourself :)).
- The net CPU power of 2 shares is the same as the net CPU power of 1 share. This does not mean that the 2-share server is not more powerful (due to RAM and bandwidth), but there is clearly a reduced difference of power between them.
- Allocating more than 20 shares to a server is only necessary if you need the corresponding RAM and bandwidth.
- 2 servers of one share each is better than 1 server made with two shares, so if you can build a distributed system, your service will be much better.
However, because of these changes to the burst CPU we have now removed the option of choosing the number of cores per server for the moment.
What does this mean for the concept of a "share"?
A "share" was originally defined as the minimum bundle of resources that would allow you to run a service with acceptable performance. Multiple "shares" could be bought as your service requirements increased. We will continue to evole what a "share" represents, but also allow you to stray from the share path by customising the resources at your disposal.
We therefore are pleased to announce that as of today, you can add RAM to your pool of available resources within increasing the number of "shares" you are using. We are going to manage RAM like disk quota. Each share comes with 256MB of RAM, but you can add additional RAM if you wish. You are free to create, for example, a 2-share server with 256MB of RAM (instead of 512) and to use the remaining 256MB on another server.
If you had bought 2 shares simply for the RAM increase and didn't need the CPU boost, you could now drop back to 1 share, and then add an additional 256MB of RAM as an add-on.
Additional Cores? Additional bandwidth?
Yes, definitely. However the "when" is rather difficult to pin down at this time, though it will probably be in the final quarter of 2010, or sooner (we have hired many new team members recently).
Is it already available?
The additional RAM is, yes. It is currently available from your resource management page. To learn how to use additional RAM, visit our RAM wiki page.
For changes to the way we manage CPU, all new servers created are already on the new model, and we will be gradually transferring the older servers to this new model as the new physical machines arrive.