The virtual network size would give you whole numbers for your replica
locations, but if you choose a keyspace size (virtual or otherwise) that
isn't a power of two, the Chord finger table keys will not necessarily
be whole numbers. Since the object of the exercise seems to be to avoid
non-integer keys, this is probably unacceptable.

Again, this is easily solved by consistently rounding, so personally I'm
not sure it is an issue. 

Still, if you are picking an arbitrary keyspace size, and really want it
to be divisible into finger tables entries, and some range of replica
factors, why not have a key space size of something like (2^42*32!).
This is the same order of magnitude as the 2^160 I think is suggested by
the Chord paper, and would allow you up to 42 whole numbered finger
table entries, and replication factors between 1 and 32, all of which
divide the keyspace evenly.


Matt

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Julien Lociuro
Sent: 28 March 2006 22:07
To: [email protected]
Subject: [p2p-hackers] Symmetric Replication for Chord

Hello Michael and Matt,
I have implemented the symmetric replication scheme too.
When the replication factor does not divide the network size I manage it
like this (illustration through an example) :
NetSize = 11
RepFactor = 3

I define a virtual network size as :
VirtualNetSize = NetSize - NetSize mod RepFactor

So here, we have a virtual network of size 9, and the replication factor
divides it.

We can though define the classes :
{0,3,6}, {1,4,7} and {2,5,8}
The keys in the virtual network are called virtual keys.

I consider that only virtual keys exist [0..8] and replication works
with the virtual network size.

The remaining keys (9 and 10) are just mapped to virtual key 0.

So items with keys 9 and 10 will be stored at the nodes responsible for
{0,3,6}

Hope that helps,

Julien.





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