Virtualisation: Miniserver VM® Technology
The basis of Miniserver VM® virtual servers
All of our Miniserver VM® virtual servers use Xen which is an open source virtualisation / virtual machine monitor or hypervisor developed by the University of Cambridge as well as IBM, Microsoft and Intel. Originally the main goal of the design and development was being able to run up to a hundred full-featured OS instances on a single computer or server. Xen provides secure isolation, resource control, quality of service guarantees and also protects each individual account on the system. The advantages of having this technology are plain and for applications such as web hosting where server load and higher amounts of processor or memory power are not needed the benefits and cost savings are huge.
More information on Xen is available on the University of Cambridge Xen Home Page.
Why are Miniserver VM® virtual servers better
One reason that Xen is more effective than commercial programmes like Virtuozzo is that operating systems must be explicitly modified to run on Xen, this enables Xen to achieve high-performance virtualization and also prevent any sharing or memory, processes or having any individual account on the server disrupting any others. Xen also allocates each account on the system its own sub kernel making it at an operational OS level a dedicated machine. This means should one Account fail or crash the others would continue unaffected. Virtuozzo on the other hand rely on the services of a single kernel, all of the VPSs on a given server must run basically the same operating system. Another major issue for Virtuozzo is reliance on a single kernel. Should the underlying OS kernel fail, all VPSs running on the server would be brought down as a result.
Xen uses a technique called paravirtualization to achieve high performance (typical performance penalties are around 2%), at the other end of the spectrum, emulation solutions entail performance penalties of around 20%.
Memset® was the first UK server hosting company to offer virtual dedicated server hosting and after extensive testing we opted for using Xen even though we had to do a reasonable amount of bespoke work ourselves to port Linux operating systems to the server. We have maintained our position as the UK leader in commercial virtual machine / VPS technology. Many other hosting companies have now jumped on the virtual server band-wagon and most of these have decided to use Virtuozzo. That is because it is very easy to set up, administer and also allows them to put up to sixty accounts on one server. We typically put roughly 15 virtual machines on each physical host server and as a result performance and uptime is excellent.
Another important consideration is that because Xen is open source unlike Virtuozzo we can keep the costs of our Miniserver VM® virtual servers lower and we do not need to put a large amount of Accounts on a Server to cover our underlying costs.
Open source advantage & the future
Being open source Xen also allows us to offer customers the ability to upgrade their kernels and also as Xen supports different operating systems on the same server we can offer customers the choice of either Debian or CentOS as underlying Linux OS. Now that Dell are supplying servers with the new Intel Virtualization Technology enabled chips, we also offer Windows Virtual Servers
Miniserver VM® virtualisation offers improved security
Key benefits to our customers
Our Miniserver VM® technology allows us to give you, the customer, a number of benefits but without the costs of a whole physical dedicated server:
- Truly dedicated server resources.
- Total separation and security, just like a physically separate machine.
- Easily scalable solutions - a few minutes of down time to upgrade.
- No overkill and wasted resource, saving power which is good for the environment & your pocket!
- More flexibility for disaster recovery such as total machine mirroring.
- A safe "play" environment; easy to reinstall and recover.
Our latest generation of Miniserver VM® host servers are Dell Poweredge R310s with 2.93GHz CPUs, 32GBytes of ECC RAM and 4 x 2TByte SATA hard disk drives in a dual RAID(1) array. Our SSD-backed host servers use four 240GByte Intel SSD drives. We choose Intel since they have proven the most reliable while many SSDs remain of questionable quality.
This specification has been honed and fine-tuned by an ongoing process of careful analysis of where the bottlenecks lie. For more information on that process, please see the post on our managing director's blog on energy efficient cloud computing.
We have advanced technology to ensure fair scheduling of CPU, disk and network resources to ensure that every customer gets at least their guaranteed minimum allocation. We do not oversell our resources.