As I pointed out in my response, you should distinguish hard and soft failures. If one machine fails even catastrophically, you can provide a new machine to replace it, thus converting a hard failure into a soft one.
The conclusion is the same. Three machines is vastly better than one or two. On Wed, Mar 31, 2010 at 1:12 PM, Henry Robinson <he...@cloudera.com> wrote: > With majority-based quorums, a 2 node ensemble will fail if either machine > fails. This is the same as a 1 node ensemble - if one machine fails, the > ensemble fails. > > But with the 2 nodes, you have (roughly) double the probability of > experiencing a single failure, with the same failure profile. >