(Illustration by Gaich Muramatsu)
> >Can CODA handle "partial replication"? That is, can it handle having files > >replicated across only some servers or does it always have to replicate > >all files across all servers? > > The basic unit for replication in CODA is the volume. You assign a > volume to a "server group". This server group may be any subset > of CODA servers you have in operation. (Well, it can't be the > empty subset :) So by this definition, CODA does handle "partial > replication". But each file within that volume is replicated ta all servers in that group, right? > >Let's say I have a system with 100 servers, each serving up files from a > >large not-heavily-used archive to a local cluster of machines. I have > >these servers in place already for other purposes; using CODA to make > >the archive available is just one more benefit. > > CODA does not serve data from other file systems. Data in a CODA > server must be stored in CODA via coda. NFS can export an existing > file system. CODA can not do this. I know what you're saying and I understand. I was thinking of a "volume" as a filesystem that is "served" by the various servers to all of the clients. The volume I was referring to was for this example the "large not-heavily-used archive". > >I'd like to be able to say that the files in this archive must exist on > >at least 3 (for example) servers at any one time, but can be held on more > >if it is convenient. Such a setting would allow me to make use of the disk > >space available across all servers (much like a raid) without each server > >having to replicate everything. Frequently used files would obviously > >get replicated across many servers (for speed) while infrequently used > >files would just reside in the minimum number of places. > > Server groups are not dynamic. When you create a volume, it is assigned > to a server group and that group of servers stores that volume and > all files in the volume. The number of servers storing that volume > does not change. Understood. I guess the next question would be if there are any thoughts about providing this feature? It seems to me that this would provide the benefits of a replicating file system along with the benefits of a raid. The total volume size would scale automatically as more servers were added to it. Brian ( bcwhite_at_precidia.com ) ------------------------------------------------------------------------------- On the road to success, you can be sure of one thing... there is never a crowd on the extra mile.Received on 2003-02-26 13:08:39