[chord] A research project in Sweden

[Emil Sit]

Thomas,

> Is the Chord project still under research and development, is it still active?

Yes, we are still actively improving our understanding of distributed
hash table routing algorithms and storage systems.  We try
to ensure that this understanding is reflected in the software that
we produce. 

> How well does Chord scale, would it scale to up to maybe 1 billion
> nodes and 10-20 billion files? (the files shared in the addressbook
> are only small addressbook entries, but there would be extremely many
> of them)

In theory, the protocols themselves scale logarithmically with the
number of nodes.

However, I am not sure that there are any wide-area p2p systems
currently that scale to billions of anything --- a quick search for the
number of concurrent Overnet users (a highly popular P2P file sharing
system) suggests they are only supporting no more than several million
simultaneous nodes.  Our implementation has never been tested with more
than hundreds of participating nodes and tens of thousands of data
items.

> Is Chord persistant (like PAST) in any way, or could it be made so?
> Under what circumstances could a file disappear from the network?

Files disappear from the network when the last remaining host
with a copy of the file leaves the system. 

-- 
Emil Sit / MIT CSAIL PDOS / http://pdos.lcs.mit.edu/chord/