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Chris Harris
Asked: 2009-07-02 08:42:36 +0800 CST

Cheap, minimal, robust web application hosting for at least three nines (99.9%) uptime?

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How can one achieve the cheapest yet very reliable web application configuration?

Let's assume at least 2 application servers for $80/mo plus a DB server will support most people's applications for a while - and we just want to achieve good reliability (at least 3 nines).

One can rent a pretty good VPS solution for around $80/mo right now from any reasonable provider (Amazon EC2, Slicehost, etc.). However, none of these VPS hosting solutions are perfect, and I've experienced more than 99.9% downtime with each of them.

I'm not sure how best to configure these 3 machines - the best would be to put the two app servers on different providers (best with different network connections) and use HAProxy to keep an eye on each other. If one fails, it will update the DNS to remove it from the pool of IP addresses for your application. But what to do about the DB server? That's still a single point of failure.

I have had issues with DNS in the past, but this can be handled by an external dedicated provider like DNS Made Easy for very cheap ($15/year). This supports dynamically modifying DNS entries if necessary as well, which is handy if you're not planning on being able to update them manually during a crisis.

Backups should be done to an external source (S3 or FTP site) at least once per day - again a minimal each month. You need an automated deploy and restore script in order to get past 3 nines I think from your backup as well.

I don't quite feel like this is quite there due to the DB availability, but it'll cost you around $80x3 + disk space + DNS = $250/mo.

Can one do better?

hosting high-availability web-applications

6 Answers

  1. Cheap, Minimal and Robust? You've just hit the evil triangle of "Good / Fast / Cheap" - Pick 2, you can't have all 3. :)

    Realistically you're doing pretty well if you can do a geographically-redundant application with failover for $250/mo.

    The only alternate I can think of would be the VPS solutions you've already had or perhaps Microsoft Azure might fit the bill.

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  2. I agree that you are doing pretty well where you are.

    Make sure that you have solid recovery processes, so that any failures that you do experience can be resolved quickly.

    "Three Nines" availability equates to roughly 8 hours of downtime in a year. If you don't count maintenance windows, that isn't a particularly demanding standard for a mainstream hosting company. I am skeptical that you have seen worse on two well regarded hosting services.

    Remember, as far as the host is concerned, once they give you a working server, you are back up. If you have a failure, and 90 minutes later they have given you another server, your downtime is 90 minutes. If it takes you three days to get it working, that additional three days is not their problem.

    The database server is clearly a single point of failure .. you have to determine your tolerance for that risk and the cost for mitigating it. I don't know much about making a DB server redundant other than that it is really hard for small systems. If that worries you, your best bet is to contract for hosting of the database itself rather than using a VPS and managing your own database server. One example (from Google, not a recommendation) can be found here; it isn't particularly expensive.

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  3. http://www.linode.com/index.cfm has been very reliable for a few of my friends. They have multiple locations and you can scale pretty easily.

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  4. I think you are facing 2-3 Problems here:

    Uptime definition

    Three nines including announced maintenance windows or excluding? How far in advance will you announce the maintenance windows?

    Hardware Uptime

    That will only scale with redundancy. You never know when it will break and three nines means only about 9h downtime per year. So even a 4h contract will grant you only one downtime (2 if it is indeed fixed within 4hours - but that's not exactly cheap to get). IMHO you have to have 2 Servers for that

    Software/Service Uptime

    Are you going to define uptime by ping reachability, HTTP answers, how? - You can easily solve that by defining in advance what you consider "up" (or if that is easier what you consider "down" - but that would be badness enumeration)

    As far as cheap goes, I don't know if by cheap you mean initial costs or running costs. You can get some cheap server nearly everywhere, but you probably need more of them to rule out hardware breakage, or get some decent hardware with HP, Dell, IBM with higher initial cost but a much lower probability of hardware breakage and thus will have a lower running cost. Just calculate over lifetime which one is going to be cheaper.

    If you just want some URLs:

    server4you was quite nice for me EC2 with georedundant locations (EU and US) could also be very interesting

    EDIT: To be clear when I say 2 Machines I mean redundant Machines per Use case (redundant DB, redundant Web, redundant DNS, redundant $whatever

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  5. Depending on your exact traffic and needs and requirements, I've hosted many smaller web apps over on 1&1 without much trouble at all.

    Other than that... pretty much any popular hosting provider out there has decent (read: published) uptimes.

    99.9% uptime means you're accepting a downtime of 8 hours, 45 minutes, 35 seconds within a one year period.

    Most decent hosting companies hit that fairly easily.

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  6. I'd recomend discount ASP.net. I like the fact that you can get a free sandbox server, and I can't remember any downtime I've seen.

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