[infinispan-dev] [ISPN-78] Alternative interface for writing large objects

[Olaf Bergner]

Am 15.04.11 16:54, schrieb Manik Surtani:
> On 4 Apr 2011, at 11:01, Olaf Bergner wrote:
>
>>> What we somehow need to avoid is chunks ending up in nodes that do not
>>> have enough memory to store them, and that could complicate things.
>> Definitely. What about replication, for instance? Does INFINISPAN use the replication mechanism suggested by Dynamo, i.e. walking the constant hash ring in clockwise direction until the desired number of replicas is reached (if I recall correctl)? I'm afraid this might fail in our case.
> Yes, this is how Infinispan's distribution works.  Just for clarification, we refer to this as distribution rather than replication.
>
> On the other hand, when we speak of replication, we mean copies are repliciated to ALL other nodes in the cluster.  I.e., each node is a replica of its neighbour, and all nodes are treated equal.  Replication, as such, has no need for a consistent hash wheel.
>
> Why do you feel this may fail?
This fear rested on the assumption that no two chunks may be stored on 
the same node. I has code in place to enforce this, yet it didn't take 
distribution into account.

Meanwhile, following Sanne's suggestion's, I removed a great deal of my 
earlier code's complexity and rely on INFINISPAN's constant hashing 
algorithm to evenly distribute chunks across the cluster.
>> Plus, I fear rehashing would have to be aware of wheter it is dealing with relocating a large object chunk or a "regular" value.
See above: if a node leaves the cluster rehashing might relocate large 
object's A 's chunk to a node that already has another chunk belonging 
to A stored. Again, this argument is obsolete by now.

Cheers,
Olaf
> Again, why is this the case?
>
> Cheers
> Manik
>
> --
> Manik Surtani
> manik at jboss.org
> twitter.com/maniksurtani
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> http://www.infinispan.org
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