8 Performance
Running a single TAO deployment for all of Facebook
allows us to benefit from economies of scale, and makes
it easy for new products to integrate with existing portions
of the social graph. In this section, we report on the
performance of TAO under a real workload.
Availability: Over a period of 90 days, the fraction
of failed TAO queries as measured from the web server
was 4.9×10−6. Care must be taken when interpreting
this number, since the failure of one TAO query might
prevent the client from issuing another query with a dynamic data dependence on the first. TAO’s failures may
also be correlated with those of other dependent systems.