On August 13, 2012 5:52:26 AM "Fernando Frediani (Qube)" <fernando.frediani at qubenet.net> wrote: > I am not sure how it works on Gluster but to mitigate the problem with > listing a lot of small files wouldn't it be suitable to keep on every > node a copy of the directory tree. I think Isilon does that and there > is probably a lot to be learned from them which seems quiet mature > technology. Could also have another interesting thing added in the > future, local SSD to keep the file system metadata for faster access. We could do that, in fact I've been an advocate for it, but it must be understood that there's no such thing as a free lunch. Once you're caching directory structures on clients, you either have to give up a certain amount of consistency or make the entire protocol much more complex to perform cache invalidations etc. Who's volunteering to do that work? Who's even asking us to do that in the core team, once they understand that it means taking resources away from other priorities and permanently slowing down development because of that complexity? Nobody. At least, unlike Isilon, there's the possibility that somebody could take a stab at reducing consistency for the sake of performance themselves (as I myself have done e.g. with negative-lookup caching and replication bypass). There's not really all that much to be learned from a closed-source system that's not even described in papers. In fact, I *know* that they learn more from us than vice versa.