Friday 6 August 2010 09:52 : Karl Robinson
We occasionally come up against pricing objections when customers compare our VMware Hosting services to other ‘VPS’ or Virtual Private Server offerings, and usually we have to explain why there’s no comparison. Sure, there are plenty of bargain basement VPS offerings out there, which on the face of it offer huge spec for crazy prices, but make sure you know what you are buying and whether or not it is fit for your needs.
I’m not going to criticise VPS providers – their products have their place in the market, but it’s important to note the differences between the average VPS product, and a higher grade VMware hosting service such as that offered by StratoGen.
So what are the similarities? Well, both services rely on virtualisation technology to carve up physical server hardware and share the resources between customers. But this is pretty much where the similarities end.
Typically, a VPS is hosted on a single high spec server with a large RAID array in it, running a hypervisor such as Parellels Virtuozzo or Citrix Xen Server. The hypervisor carves up the physical server into multiple virtual servers or VPS. The VPS will generally only ever reside on that one server and will compete for resources with all of the other VPS’ on that server. So, if another VPS gets busy, this could potentially impact on the resources available to your VPS, and slow things down for you.
The server hardware is often unbranded – the cheapest that the provider can get away with, and disks may be slow SATA disks with huge capacity. Slow high capacity SATA disks will have poor IO performance, so are not great for IO hungry applications such as databases.
Also, because the VPS resides on a single box, if anything in that box fails, all the VPS on it will fail. VPS providers may have an SLA around restoring servers in the event of a hardware failure, but this may require them to restore the VPS to another physical server, which will take time – downtime for your VPS.
With StratoGen VMware hosting, none of the above issues apply. VMware manages resources across a pool of hardware, or cluster. The cluster is made up of enterprise class HP blades. Storage is on a separate Dell EqualLogic iSCSI Storage Area Network (SAN) with 15K RPM SAS Drives – great for IO hungry applications. VMware still carves up the physical hosts in the cluster into multiple virtual machines, but these virtual machines can run on any host in the cluster. So, if a physical host gets busy, VMware can automatically move virtual machines from the busy host to one with more resources available, and it can do this in real time, without shutting down or even affecting the performance of the virtual machine. This ensures that all customers get the performance that they are paying for.
In the event of a physical host in the cluster failing, all of the virtual machine data is stored on the SAN, so VMware can simply boot up the failed virtual machines onto a spare physical host (which are always kept in an N+1 configuration), thus ensuring minimal downtime, and all without any human intervention.
So whilst on the face of it there may seem little difference between VMware Hosting and VPS, it’s clear that there are some marked differences. VPS is fine if you are hosting a lot of static brochure ware websites which rarely get visited. But if you’ve got a busy database driven website or online application, check out the VPS credentials very carefully, or choose VMware hosting.