March 26th, 2012
Mike Solomon, one of YouTube's original engineers, has learned a great deal about scalability over the last seven years:
Jitter – Add Entropy Back into Your System
[...] Systems have a tendency to self synchronize as operations line up and try to destroy themselves. Fascinating to watch. You get slow disk system on one machine and everybody is waiting on a request so all of a sudden all these other requests on all these other machines are completely synchronized. This happens when you have many machines and you have many events. Each one actually removes entropy from the system so you have to add some back in.
Also (this one is my favourite)…
Cheating – Know How to Fake Data
[...] The fastest function call is the one that doesn't happen. When you have a monotonically increasing counter, like movie view counts or profile view counts, you could do a transaction every update. Or you could do a transaction every once in awhile and update by a random amount and as long as it changes from odd to even people would probably believe it's real. Know how to fake data.