We're currently using AppLogic from 3Tera and it provides us with complete isolation so we can't oversell our servers and all the resources are guaranteed to be there. This includes CPU, RAM and Disk. I could be wrong about this, but Xen also has this feature.
We've been trying to find new ways to keep testing the grid so if anybody has any suggestions, feel free to PM or email me. We've been testing out cPanel servers, game servers and various other applications.
Xen has this feature for Disk space and Memory, but CPU and Disk I/O it does not.
Think about how much your paying and what your getting, if your using 100% of one of their CPU's and you only have a 512MB VPS, then they have to think of their other users on that machine.
This is a problem with Equal Share, they do not limit your CPU usage, you get an equal share of the CPU. Therefore if you are constantly using more than your share, you will get suspended. This is also a reason why $30 VPS's will benchmark over 200 scores in the unixbench because they can utilize lots of CPU.
However since you weren't utilizing dedicated CPU, this is what can happen.
Disk I/O is really hard to limit, on HyperVM - you can set CPU limits with OpenVZ. It saves us a lot of hassle, especially when customers tend to use a lot of CPU - we can just work with them to set a cap on it. I also find it kind of harsh that company would totally cancel an account for over utilization, I would think they would dispatch an email, and then if the matter was that serious - they would just turn off the VPS until they resolve the matter, not delete / cancel it.
Virtuozzo 4 includes disk I/O priorities and the very latest kernel also had an option to disable fsync operations inside a VPS -- this prevents a single VPS from causing many processes to enter the Disk-Wait state.
Other than that we personally use CPU Units (proportional share system for dividing CPU allocation based on priorities) and CPU Limit (cap of total % of CPU used -- % is based on plan). There is also a limit on how many CPU's a VPS can see. Most CPU QoS issues are due to misconfiguration under Virtuozzo. Virtuozzo 4 also includes a "burstable" CPU option where VPS's can burst to the full system for a few seconds before they get limited to their CPU Limit. This means they are not hurt for quick bursts, but excessive usage get limited.
Matt Ayres - togglebox.com
Linux and Windows Cloud Virtual Datacenters powered by Onapp / Xen
Instant Setup, Instant Scalability, Full Lifecycle Hosting Solutions www.togglebox.com
Most host's usually give you Gauaranteed stuff. The biggest thing that i see is that they "share CPS" so that it is equal. Most places also put in their TOS that if you use over 25% of the cpu for 15 seconds for say, they will suspend you.