At least they ditched Oracle (licensed)...
Oracle has a nasty licensing model where they charge you per core regardless of if that core is a physical one or not (hyper-threading). While I was there, it suites told all the engineering managers that Oracle was out and the going forward solution was Microsoft SQL which, as I understand, has more relaxed licensing model.
Another thing I'm wondering about is I would figure Netflix to be big enough to have SAN storage. Just about every large company I worked at always used SAN replication technologies instead of open source stuff. And it's not a debate about open source solution vs. commercial. It's more about support. Large companies want a throat to grab when things break bad.
That was a sad day.
That's why you then switch to their T5 or M-series with up to 3,072 processors, and then Oracle comparatively charges you peanuts, since those systems have relatively few physical sockets. And if you know SPARC, and you know Solaris, you can squeeze some serious savings. The problem, it seems to me, is that most system administrators and managers today are neither familiar with SPARC nor with Solaris, so they end up paying more in the long term in licensing and maintenance for running something else like MySQL on GNU/Linux.
But that's their problem, not the guy's who knows SPARC and Solaris and how to save money, isn't it?
Sorry, should have been more clear.
As a follow up. Many projects I was involved with did use Oracle replication but it was a rolling log file type that was purposely delayed to account for mistakes. Rolling replication happen across geographic locations while SAN replication dealt with the hot fail-over situations locally.
Large companies have an enterprise wide license of the Oracle database, so they have thousands of instances (worked at a place like that, that's how I know), and at that point, with that kind of scale, Oracle becomes dirt cheap, considering it delivers the only database I have seen that can withstand the kind of abuse a large institution can throw at a relational database management system.