Derivante

A couple weeks ago I began working with EC2 and RightScale in preparation of our big IT infrastructure change over. Ill start by giving a brief overview of our hardware infrastructure. Currently we're running the CitySquares' website on our own hardware in a Somerville co-location not too far from our headquarters in Boston's trendy South End neighborhood.

From the very beginning our contract IT guy set us up with a extremely robust and flexible IT infrastructure. It consists of a few machines running Xen Hypervisors with Gentoo as the main host OS. Running Gentoo allows us to be as efficient as possible by specifically optimizing and compiling only the things we need. While this is a good step, it is Xen that really makes the big difference. It allows us to trade around resources as we see fit, more memory here, more virtual CPUs there, all can be done on the fly. For a startup or any company with limited resources this is rather essential. You never know where you are going to need to allocate resources in the months to come.

While this is all well and good, we are still limited when it comes to scaling with increasing traffic or adding additional resource intensive features. We have a set amount of available hardware and adding more is an expensive upfront capital investment. Not only that but in order for us to really begin to take advantage of Xen and use it to its full potential we were presented with an expensive option, it required the purchase of a SAN and more servers. For those in the industry I don't think I need to mention that these get expensive in a hurry. This would have been a huge upfront cost for us, one we didn't want to budget for. The second option, which is the one we eventually went with was to drop our current hardware solution and make the plunge into cloud computing with Amazon's EC2.

Here I am now. A couple of weeks into the switch with a lot of lessons learned. There are definitely pros and cons for each platform, either going with EC2 or rolling your own architecture. Before I get into the details I want to make clear that there are many factors involved in choosing a technology platform. I am only going to scratch the surface, touching upon the major pros and cons with respect to my own opinions with best interest for CitySquares in mind.

Let me begin by starting with the pros for running your own hardware:

• The biggest pro is most definitely persistence across reboots. I can not stress the importance of this one. You really take for granted the ability to edit a file and expect it to be there the next time the machine is restarted.

  • You only need to configure the software once. Once its running you don't really care what you did to make it work. It just works, every time you reboot.

  • UPDATE 8/21/08: Amazon releases persistent storage.

• Complete and utter control over everything that is running. This extends from the OS to the amount of RAM, CPU specs, hard drive specs, NICs, etc. The ability to have a economy or performance server is all up to you.

• Rather stable and unchanging architecture. Server host keys stay the same, the same number of servers are running today as there were yesterday and as there will be tomorrow.

• Reboot times. For those times when something is just AFU you can hit the reset button and be back up and running in a few minutes.

• You can physically touch it... Its not just in the cloud somewhere.

Some cons for running your own hardware:

• Companies with limited resources usually end up with architectures that exhibit single points of failure.

  • As an aside, you can be plagued by hardware failures at any time. This usually is accompanied by angry emails, texts and calls at 3am on Saturday morning.

• Limited scalability options. For a rapidly expanding and growing website, the couple weeks it takes to order and install new hardware can be detrimental to your potential traffic and revenue stream.

• Management of physical pieces of hardware. Its a royal pain to have to go to a co-location to upgrade or fix anything that might need maintenance. Not to mention the potential down time.

  • Also, there are many hidden costs associated with IT maintenance.

• Up front capital expenditures can be quite costly. This is especially true from a cash flow perspective.

• Servers and other supporting hardware are rendered obsolete every few years requiring the purchase of new equipment.

These pros and cons for running your own hardware are pretty straight forward. Some people might mention managed hosting solutions which would mostly eliminate some of the cons related to server maintenance and hardware failures. However, this added service comes with an added price tag for the hosting. Whether it is right for you or your company is something to look into. We decided to skip this intermediary solution and go straight to the latest and greatest solution which is cloud computing. To be specific we sided with Amazon's EC2 (Elastic Compute Cloud) using RightScale as our management tool.

Some of the pros for using EC2 in conjunction with the RightScale dashboard are as follows:

• Near infinite resources (Server instances, Amazon's S3 Storage, etc) available nearly instantaneously. No more Slashdot DoS attacks if everything is properly configured and set to introduce more servers automatically. (RightScale Benefit)

• No upfront costs, everything is usage based. In the middle of the night if you are only utilizing one server thats all you pay for. Likewise, if during peak hours you're running twenty servers you pay for those twenty servers. (Amazon Benefit, RightScale is a monthly service)

• No hardware to think of. If fifty servers go down at Amazon we wont even know about it. No more angry calls at 3am. (Amazon Benefit)

• Multiple availability zones. This allows us to run our master database in one zone which is completely separate from our slave database. So if there is an actual fire or power outage in one zone the others will theoretically be unaffected. The single points of failure mentioned before are a thing of the past and this is just one example. (Amazon Benefit)

• Ability to clone whole deployments to create testing and development environments that exactly mirror the current production when you need them. (RightScale Benefit)

• Security updates are taken care of for the most part. RightScale provides base server images which are customized upon boot with the latest software updates. (RightScale Benefit)

• Monitoring and alerting tools are very good and highly customizable. (RightScale Benefit)

Some of the cons for using EC2 and RightScale:

• No persistence after reboot. I can't stress this one enough! All local changes will be wiped and you'll start with a blank slate!

  • All user contributed changes must be backed up to a persistent storage medium or they will be lost! We back up incrementally every 15 minutes with a full backup every night.

  • UPDATE 8/21/08: Amazon releases persistent storage.

• Writing scripts to configure everything upon boot is a time consuming and tedious process requiring a lot of trial and error.

• Every reboot takes approximately 10-20 minutes depending on the number and complexity of packages installed on boot. Making the previous bullet point even that much more painful.

• A few of the pre-configured scripts are written quite well. The one for MySQL is as good as they get. You upload a config file complete with special tags for easy on the fly regular expression customization. The Apache scripts on the other hand are about as bad as they get. Everything must be configured after the fact.

  • With Apache however, you'll be writing regular expressions to match other regular expressions. Needless to say is a royal pain and you usually end up with unreadable gibberish.

So there you have it, take it as you wish. For CitySquares, EC2 and RightScale were the best options. It allows us to scale nearly effortlessly once configured. It is also a much cheaper option up front where as owning your own hardware is generally cheaper in the long run. We did trade a lot of the pros of owning your own hardware to get the scalability and hardware abstraction of EC2. It was a tough decision for us to switch away from our current architecture but in the end it will most likely be the best decision we've made. The flexibility and scalability of the EC2 and RightScale platform are by far the biggest advantages to switching and in the end its what CitySquares needs.