On Tue, 13 Nov 2007, Bryan Henderson wrote:
quoted text
> >Ceph is a distributed network file system ...
> 
> What's distributed about it?  As described, it sounds highly centralized. 
> Do you mean it is distributed across the nodes of the central server 
> clusters?  Or just that it's a shared filesystem (multiple clients can use 
> it at the same time)?

Both, actually, although there isn't necessarily a strong distinction 
between the 'central server cluster' and client nodes.  For example, 
storage nodes can double as client nodes (as in a cluster doing 
distributed computation or some such thing).

The system is distributed in the sense that there is no central server 
limiting scalability.  Data storage is distributed across a large cluster 
of storage nodes (bricks or OSDs), and the metadata (namespace) is managed 
by a smaller cluster of metadata servers, allowing shared access to the 
filesystem by many many clients.  Aggregate I/O throughput and capacity 
can be scaled more or less independently from metadata throughput 
(namespace manipulation) by adjusting the number of nodes devoted to each.

sage
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