Delivering web software on a VPS

Much of my time is spent as a developer of web related software1. But recently I've found it impossible to avoid being drawn into some quite complex hosting issues - for handling my own sites and those of clients. Experts in internet related software will be familiar with the problems I have found; many software developers will be less familiar with them. This article is intended to help those who, like me, approach the use of hosting with less than comprehensive knowledge of the area.

Shared hosting has been familiar for some time, and often resource limits on processing or memory have not been particularly apparent to the user of the service. Lately, the use of a Virtual Private Server (VPS) has rapidly gained in popularity. Prices have fallen dramatically, virtualization is trendy and there are some perceived advantages. However, the available resources are rather more tightly controlled than in most shared hosting. Although there are other considerations, my focus here is on questions of resource management in a VPS.

Before we go into the detailed issues, though, let us consider the gains to be made through use of a VPS. One gain is said to be having root access to the server, or at least to the virtual server that is being rented. This is obviously a mixed blessing. It does mean that many aspects of the server can be tuned to suit the purpose for which it is being used, and the user of the VPS is free to make changes without considering anyone else. The downside is that you need to know what you are doing in order to benefit from this, and a good number of people buying a VPS have little or no idea where to start. Significant time and effort needs to be spent to see any gain.

Another gain, and the one that most attracted me, is that a VPS should be relatively protected from resource overloads caused by other people on the same server. On the basis of my personal experience, this advantage is only partly realised. The more extreme incidents where a server almost grinds to a halt, dragging down every site, seem to be avoided. On the other hand, there are still significant variations in performance that appear to be caused by factors outside my own VPS.

Let me explain how I came face to face with some quite complex resource issues in VPS management. My reseller account for shared hosting was working quite well, providing for both my own sites and a few client sites. The provider was a US based host, which suited me quite well as US hosts seem to be able to provide good value for money as well as being a suitable location for material that is being delivered globally. But the issue of performance troughs caused by other sites on the same server was irking me. The host had apparently done quite a lot of work to improve SQL that was the cause of the problems, but there were still concerns. So I started looking around.

After a few experiments with shared schemes, a VPS started to look attractive. As I am based in the UK, it seemed worth looking to see if a European host could provide a good service. Following a brief selection process, I signed up with a UK host for a managed VPS at the lowest level that was claimed by the host to be suitable for use with cpanel. I wanted cpanel for the benefit of clients whose site hosting was my responsibility. It was not long before I started to experience problems. Services were repeatedly failing.