Tugger the SLUGger!SLUG Mailing List Archives

Re: [SLUG] today's scary thought


Nick Andrew <nick@xxxxxxxxxxxxxxx> writes:
> On Fri, Jul 16, 2010 at 12:31:42PM +1000, Daniel Pittman wrote:
>
>> Also, lots of different apps, so I might well end up with multiple
>> solutions.
>
> This seems likely. Databases have different consistency requirements to
> people.

One of the attractions of Cassandra is that it allows the client to specify
the consistency level required, from none, through to "every node ever", or
quorum, or whatever.

I need to look further at Riak to work out how well their model expresses the
same, although as they don't do cross-WAN out of the box it has a lesser
problem to contend with.


>> A good distributed POSIX FS with replication, eventual consistency, some
>> sensible conflict resolution model, and data center awareness would have
>> been easy enough to use though.
>
> Conflict resolution is the problem. The less of that you want, the more
> synchronous your filesystem has to become - or expose more non-POSIX
> filesystem behaviour to applications.

*nod*  Very true.  I think, for most people, the Dropbox model of conflict
resolution would be great to have in a file system:

Find a conflict, generate two documents, one with each version.  Viola, you
just punted the hard problem up to a human.

Less good for machines, naturally, although a similar process can help.

        Daniel
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