That's right, it should be noted however that the need of horizontally scaling the equivalent of the NameNode kicks in only when you really have a very large st

That's right, it should be noted however that the need of horizontally scaling the equivalent of the NameNode kicks in only when you really have a very large storage system, where large can be defined as: "You know you have a large storage system when you get paged at 1 AM because you only have a few petabytes of storage left." [1] Even if you are below that size you might have a large system, and even if using a single metadata master node might be a sound solution you still have lot of interesting problems to solve. Don't make systems more complex than necessary. More pointers to google public material on colossus in [2]. [1] http://static.googleusercontent.com/media/research.google.com/it//university/relations/facultysummit2010/storage_architecture_and_challenges.pdf http://static.googleusercontent.com/media/research.google.co... [2] http://www.highlyscalablesystems.com/3202/colossus-successor-to-google-file-system-gfs/ http://www.highlyscalablesystems.com/3202/colossus-successor...