Re: [infinispan-dev] DIST and CAP
On Fri, Mar 23, 2012 at 12:53 PM, Bela Ban <bban(a)redhat.com> wrote:
Changed the subject...
I got unsure about what Infinispan's DIST mode provides with respect to
CAP (see below).
I would argue availability and partitioning, but not consistency, as a
network partition and subsequent healing might lead to incorrect values...
Thoughts ?
On 3/22/12 3:33 PM, Dan Berindei wrote:
>> We're trying to provide the C, the A and the P (of CAP), with perhaps a
>> slighly degraded A. This may not be feasible... especially on large
>> clusters where nodes come and go with a higher frequency than in a small
>> cluster.
>>
>
> Slight correction here: we are only trying to provide C and A. We
> don't really have anything to handle P yet...
I think I may have mixed up concepts a bit here... what I meant to say
is that we kind of give up in the presence of network partitions.
Actually you're right, we only give up on consistency - the partitions
are still available and respond to requests, even if their responses
are inconsistent.
Probably the only way to get consistency during a network partition is
to stop responding to any requests, so clearly we can't provide C all
the time.
But I don't think it's fair to say that we provide A and P, because in
fact we do sacrifice availability for consistency during state
transfer. And as long as we don't have any network partitions, we even
manage to provide C (for sync+tx caches at least).