Bill Carlson <bill-carlson_at_uiowa.edu> wrote
> 
> On Sat, 11 Sep 1999, Jan Harkes wrote:
> 
> > However, it does support multiple servers within one administrative
> > cell. And volumes can be replicated across several servers.
> > 
> > The codasrv itself doesn't care whether it is an SCM or not, the other
> > daemons have to know it because of the simple replication technique of
> > copying the files in /vice/db from the SCM to the other servers.
> > 
> > Jan
> >
> 
> Hello,
> 
> How intelligent is the replication? Suppose I spread a volume across four
> coda servers, do I get a space benefit or mere redundancy of data? 

There are probably no saving in space, but only enhancement of 
availability.

Coda uses a "read-one, write-all" strategy when strongly connected,
and a "read-one, reintegrate-with-one-and-resolve" strategy when weakly
connected. ("one" and "all" here refer to the servers)

The former is in as early as 1990 (see Satyanarayanan et al. 1990, 
Section IIIA), the later is in around 1995 (see Mummert 1996, 
Section 5.3.5).

Enjoy the reading !

Satyanarayanan et al. 1990:
	author = "M. Satyanarayanan and J. J. Kistler and P. Kumar and 
                 M. Okasaki and E.  Siegel and D. Steere",
	title = "{Coda: A Highly Available File System for a
                Distributed Workstation Environment}",
	journal = "IEEE Transaction on Computers",
	volume = 39,
	number = 4,
	month = "April",
	year = 1990,

Mummert 1996 (Phd Thesis):
        author = "L. B. Mummert",
        title = "Exploiting Weak Connectivity in a Distributed
                 File System",
	school = "Carnegie Mellon University, School of Computer
                 Science ",
	year = 1996,
        (this one is available on the Coda web site)

-- Clement
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