Geek alert! This article is for Slicehost geeks only.

Talk about playing on the edge, I almost fell off this time. I have eight slices (virtual servers, that is) on Slicehost (which is now owned by Rackspace) and believe me they are tiny!^[1] But they can serve low-volume to medium-volume web sites pretty well. For instance, Shaping Youth (several thousand visitors a day) and GirlsHorseClub are on these little servers and they serve up pretty rapidly.^[2] Nice thing about Slicehost is that any host can be scaled up from the tiny size to 16x that size, and because it’s cloud computing, you can also bring up multiple instances of any server and have them share load. This allows me to implement the traditional three-tiered architecture (web/application/database) quite well without having to worry about whether my servers will be able to handle the load because I can scale ’em up whenever I need to.

But, the catch is that when you start with the tiniest slice (256MB RAM) you really have to fine-tune your operating system and applications in order to get good performance out of them.

This has led me to some fun discoveries about 1) how to make Apache work in a really tight space; 2) how to add additional web serving using NGINX (engine-X); 3) how to run MySQL in less space; and finally 4) how to use Java and Tomcat wedged into a non-existent memory slice.

Today’s lesson for me was installing Tomcat 5.5 on Slicehost. I started by reading How to Install Tomcat on Ubuntu in the mkyong blog. Not bad at all. The essence is to first find out what version of Tomcat is available on your slice:

sudo apt–cache search tomcat

Then install that version and the admin app for it:

apt–get ––fix–missing install tomcat5.5
apt–get ––fix–missing install tomcat5.5-webapps
apt–get ––fix–missing install tomcat5.5-admin

Then I like to have /usr/local/tomcat defined (like on all my other servers):

ln –s /usr/share/tomcat5.5/server/ /usr/local/tomcat

That was about all it took. It serves by default on port 8180 – and the admin app was there and ready to go. My next step was to port a Java app that I have been running on bigger servers over to this little server. That actually worked quite well, requiring about 6 hours to port, recompile (to eliminate a few warnings) and test.

[2] These two slices actually had to be boosted to 512MB recently in order to handle anticipated high traffic. But I can reduce their size after the stress-out period passes.

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I’ve mentioned before that I’m bringing up web sites on Slicehost. It’s a cloud computing environment and that means I don’t know and don’t care exactly what or where the server is, and I only buy as much as I need.

It’s an interesting experience because in the rest of my life I’m constantly expanding my (personal) computers by adding storage and processor power so they can run faster and faster, but in the case of cloud computing, instead, I’m scaling down the pieces of software so they can run more efficiently in a small “computer” instead.I was wondering a few days ago why one of my slices was running so “hot” – it was using up all of its memory and it was swapping to disk like crazy. I thought that Apache (web server) and MySQL (database) would be smart enough to make good use of whatever memory was available, whether it be large or small.

So in the interest of geekiness I took a look at what I could do to save the situation.

Turns out that my reducing the number of processes that Apache is allowed to run, and my using an example configuration file that MySQL provides for small installations, I was able to tune my slice so that it hardly ever swaps (which reduces disk utilization to minimum) and just barely fills up the available RAM in the virtual computer.

Here are the references that were most useful to me in this process. It probably took me 30 minutes to get it all tuned up. And wow it runs great now!

• Lowering Apache memory usage (just read the Apache part, not the MySQL part)
• Finding and using the my-small.cfg MySQL configuration file (this is specifically designed for Slicehost, which I use)

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Cloud Computing– it’s a relatively new term for a relatively old concept. For at least six months now I’ve been thinking about two inevitabilities: 1) that my servers will fail some day soon; and 2) that I may have to rapidly scale (up) some customer’s site because it will suddenly have traffic needs well beyond the capacity of my servers.

The answer is pretty obvious to me – I’ll soon be eliminating my own serves in favor of purchasing computing power in whatever quantities I need at the time. Scalable on demand. From one of the cloud service providers that are coming online now.

Buying cloud computing essentially means buying computing power without knowing or caring exactly where it is physically located or what type of equipment it’s on. Someone else buys the servers, puts them in racks, powers them, cools them, and connects them to the Internet. And they stand there ready to go into service whenever they’re needed.

I looked at Amazon EC2 first, because it’s been getting a lot of publicity. Amazon has built server farms that could scale up and down rapidly, and has been supporting its own services on those computers, for years. It’s was logical that they’d be in a position to sell “time” on servers to anyone who wants it…as long as they had the spare capacity. But Amazon charges $0.10 per hour for a basic “server” instance, which means $2.40 a day or over $72 a month for even one server. That’s pretty close to what I was paying Verio for a virtual private server in the late 1990s, and it’s probably 50% of what it costs me to have my own server with several times the capacity.

Then I ran across a company called Slicehost – recently acquired by Rackspace. These guys offer raw server instances (virtual private servers) starting at $20 a month. These $20 “slices” are small, but they get the job done and they’re ideal for hosting web sites that are simple, have low traffic requirements, and yet might have to be scaled up at a future date. To scale, you access the Slicehost online control panel, and within minutes you can have a much larger slice of a server – still “private” – with literally the click of a button.

Oh, and the “private” is important. My clients need pretty tight security, and running a web site on a virtual private server means they don’t have to worry about some other user of the same server having a weak password and getting hacked, consequently opening up a window to my client also getting hacked. With a virtual private server, there’s only one user, and you’re responsible for your own problems.

So the site you’re looking at right now is on Slicehost. On their smallest and cheapest offering. And yet handling the traffic pretty well. And on top of that, I have several sites all on the same slice. This isn’t for the faint of heart – I had a Ubuntu 8.04 server instance installed and from there I installed all of the services I needed, but this really requires some middling sysadmin expertise. (Takes me under an hour to provision one slice and bring up a WordPress instance. Then about 30 minutes for additional WordPress instances or web sites.)

This is the future and it’s slick.

Oh, by the way, the new look of the web site is not related to the switch to Slicehost. I just got tired of the old look, and loved this new theme, and switched over during the migration to Slicehost.

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