Introducing TDIK

(obdisclaimer: I don't speak for my employer here, and this is my idea, not theirs.)

Quick summary: Applying machine learning to uncover bottlenecks, predict system capacity, user growth, hardware purchases, and, generally, everything you need to know when running a service-based business. You give it your monitor data, and it gives you a diagnostic and predictive model of your system.

Time Data Into Knowledge (TDIK) is an idea I had a little over a year ago. Since I've talked with several people about it in that time, it's no longer patentable in the US. And, since I haven't actually done more than a proof of concept, I wanted to make a full public disclosure of the idea, in the hopes that it would inspire someone.

Imagine you have a multi-tier application stack, with fairly complete monitors. So, your frontend server, the message queues, databases, and a few backend processes (bulk and on-line). Additionally, assume you've got complete monitors in this stack: the normal machine telemetry (CPU usage, disk capacity, network utilization, etc), as well as application-specific stuff, like number of users, hits per second, message queue depth, etc.

Traditional monitoring systems give you graphs of all this; you do the analysis. The best you can hope for is a big display of all your graphs together, then eyeball them for correlations. You can shuffle them around to make it easier, but it's still human work. This kind of correlation is great for fires, where you have a sudden large shift in two variables and don't care about the precise magnitude of the relations. It's no good for a more valuable, big-picture task: capacity planning, where the relationships are less pronounced and more complicated.

That's where TDIK comes in. There are ways to find out how correlated two datasets are and then extract models of their relationship. You can expand these out to any number of combinations, though it gets much more computationall expensive. Once you have these models, though, they're invaluable.

You can make a model of your system yourself, using your knowledge of it. Your model will probably be darned good, since you built the thing. I've done these, and not only are they fun, they're handy. But there's always dark corners lurking around. What's the performance interaction of running MySQL and Squid on the same host, for instance? They're both memory-intensive, especially when big requests are getting bandied about. Ideally, I'd have separate hardware for them, but, well, you know how that goes.

TDIK, since it's learning the model from scratch every time, will find out how things interact on your particular system. It discovers correlations that don't seem straightforward, but make sense after the fact. Things like "Webserver load is highly correlated with the number of user profile views in full mode" (you eventually discover that someone accidentally left in the debug code that disables template caching there).

TDIK's models are useful for more than troubleshooting, though. You can also use them for planning. For instance, let's say your website has N concurrent users. Would you like to know how many users the current system can support? The model can tell you how many, and which component will be your bottleneck. Or, perhaps you know that you want to be able to support some number of users. The model could tell you how much you'd need to scale each component in your current system to get there.

What about firefighting? Your model reflects the steady-state performance of the overall system. If you have the last few minutes of monitor data, you can quickly re-correlate and see which components don't fit the model. In fact, you can see exactly how much they don't fit the model, and prioritize the order in which your team checks things out.

But why firefight in the first place? Using that same correlation, you can get alerts when the current state deviates appreciably from the model. One things I've always said about nagios alerts is that "They're only as good as your experience and creativity." If you don't know that a failure mode is waiting, you're not going to have a nagios alert prepared for it. TDIK's model obviates that, since it knows your system intimately. It will notice the increase in CPU time versus page hits even if the raw number of hits is low (say, at midnight), letting you identify and avert the morning meltdown.

"So where do I download or buy this product, or pay for the service?" you ask. Well, it's mostly still vapor. I did a small proof-of-concept, and found that modelling this many variables is noisy. And, honestly, I haven't had time to make this happen. It could probably be a startup, but I'm not certain of it yet. Feel free to drop me an email at if you feel otherwise.