Coda File System

Re: Q: Is Partial Replication Possible?

From: Brian White <>
Date: Wed, 26 Feb 2003 14:35:36 -0500
> > > 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.
> I've already modified the client to the point that it should be able to
> handle it. We just need some callback that forces a client to refetch
> the information about which servers actually hold a volume replica.
> Ofcourse this has never been tested because...

Now, as I understand it, you're talking about replicating a complete
volume on an additional server.  I was thinking of a resolution more on
the file level.

A new server in the group would initially start out as just a blank holding
disk.  When it needed a file, that file would be fetched and cached locally.
Once held on this new server, another server could purge its copy to make
space for something else it would like to cache.  As long as there were
at lest three (for example) other copies out there somewhere, a server
would know that it was free to purge its local copy and the system as
a whole would still meet the minumum required redundancy.

                                 ( )

            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 14:37:44