I often like to try out different VPS providers, as listed on http://lowendbox.com/. There are normally 2-3 offers posted there every day, so it can be a difficult to know who to go for. Here is what I look out for:
Cost
Obviously, on a website like LowEndBox, you are unlikely to get anything which is expensive – but it’s relative, of course. Some offers are much better value than others – although the value is normally judged on the below criteria. You should also consider how they bill you – is it monthly, quarterly or do you have to pay for the whole year in advanced? If it’s latter, then you should ask yourself if the host is reputable – it’s no good paying for a years worth of hosting if they shut up shop after two months.
Location, Location, Location
Location is one of the most important factors for me, as it is one of the determining steps in the latency between your network, and the VPS’s network. Typically, the nearer the VPS to you, the lower the latency (or ping) between you and it. This is particularly important if you are running something game server, although it can be noticed with things like web page load times, too.
RAM
This is also very important – the amount of RAM your VPS has will determine how many programs/servers/daemons you can run concurrently. If you are serving static pages, then you wont need much ram – but once you start delving into mySQL, Rails and other memory-intensive applications, you will need more and more RAM for your VPS to keep running smoothly.
It should be noted that OpenVZ and Xen manage memory differently. OpenVZ has “guaranteed” memory, and “burstable” memory. The guaranteed memory will ALWAYS be available to you, no matter the time of day, or how many other people are using the server at the same time. Burstable memory, however, is not always available and should not really be relied upon, especially if you plan on using it for long periods of time. It is the memory which is not currently in use by other VM’s, which you can use for a small amount of time – it is especially useful for things like compiling software, or even just updating software.
Xen, however, has a more “traditional” type of memory management. You have RAM and Swap Space, and they act pretty much as normal. The RAM is guaranteed, and the swap space is a file on the hard drive which can be used as RAM. It is no where near as fast as RAM, but some higher-end hosts use SSD’s for your swap space… although I have no experience with such luxuries!
With Xen HVM, you are allocated a certain amount of memory, and cannot exceed it. However, the hard drive can be partitioned, allowing you to create swap partitions.
CPU
The CPU that your VPS Host uses in their nodes (the physical machine that is hosting your VPS) is pretty important, too. Some of the sneakier lower end hosts use desktop-grade hardware. While this is not AUTOMATICALLY an awful thing, some people find it more re-assuring when Opterons or Xeons are used in place of the popular Q8200 or Q6600. While hardware failure is not your responsibility, downtime can be very frustrating – and depending on the components used, you might get a performance hit if your host uses consumer-grade components. Some hosts limit you to a certain number of Processor Cores, or limit you to a particular clock speed (Host Rail springs to mind) – this should be checked.
Hard Drive
The amount of disk space you need obviously depends on what you are using the VPS for – an image hosting website would use more than an IRC bouncer… So there is not much to be said on that front. One thing that should be watched out for is the type of disk they use. SCSI drives are typically much faster than SATA drives, but they typically hold much less and are more expensive. It is no good having a SCSI array if there are 40 users on the system, all of whom are using BitTorrent – you may as well be using a 1.44″ floppy drive as your hard disk. To check the average write speed of a host, have a look at this Low End Talk thread – while most hosts operate multiple nodes, it should give you a rough idea of what to expect.
Network
Following on from my second point about location, latency is important. Most good web hosts will provide you with an IP which you can ping to determine the latency between the two networks, and will also have a speed test file (typically a 10mb/100mb/1gb) which you can download to see what kind of throughput the VPS is capable of. You should also keep your eyes open for the amount of bandwidth you are allowed – some hosts operate 100mb/s lines, with xGB’s bandwidth allowance – others cap your speed at 10mb/s or so, but don’t count the amount of traffic that you transfer. It’s your choice when it comes to this – I personally prefer a fast connection with a limit (especially if they dont have bandwidth over-usage charges, and simply cut you off for the rest of the month), but others may prefer a limited speed with no measured transfer limit.
You should remember that if you plan on using the VPS as an OpenVPN server, then the amount of bandwidth you require will be roughly twice the amount that your computer will download – OpenVPN has to both download and upload, doubling the traffic.
Operating System Range/Control Panel
This is fairly obvious – you should consider the range of operating systems that the host has on offer. Many hosts are willing to make other OS’s available to you, but it’s not a given right. You should check their OS list, and if you dont see what you want, then you should ask them.
There are a few VPS control panels around – the most popular is SolusVM. It’s a personal preference, but I like SolusVM (there is even an iPhone App that will let you reboot/shutdown your VPS while you’re out and about… not that I have ever needed too!). Some hosts let you upload your ISO’s when you are using Xen HVM – ThrustVPS springs to mind on that one. You should probably check that out with the host you are looking at – it’s not a terribly common feature.
TOS
You should check the Terms of Service of your potential web host before you sign up to get hosting from them.Most hosts don’t like you using BitTorrent, and state this in their terms of service. Some hosts disallow anything to do with IRC – others dont like you using lots of CPU time, so it’s important that you check.
Support
Last but not least is support. You should check to see if your potential host has got a live chat service – if so, how often are they online? ThrustVPS has a good live chat service, and where almost always online when I needed them. BuyVM has got an IRC Channel, which is useful, as other users often hang out there – you can ask if it’s just you experiencing an issue, or if it’s a server-wide problem. Not having live chat/IRC support isn’t necessarily a bad thing. As long as the staff are knowledgeable and friendly, and have a quick response time, then you should be OK. A quick way to test this would be to submit a ticket asking something Semi-technical – for instance, “Do you support TUN/TAP?”, or “Can I use a custom kernel”. Their response will help you gauge how they will respond in the future.