[Gluster-users] Problem with too many small files

[Jeff Darcy]

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.