[p2p-hackers] p2p in some place or other

[Nazareno Andrade]

Hi there.

A nice paper which you may find useful in this thread:

High Availability, Scalable Storage, Dynamic Peer Networks: Pick Two 
(HotOS XI)

Peer-to-peer storage aims to build large-scale, reliable and available 
storage from many small-scale unreliable, low-availability distributed 
hosts. Data redundancy is the key to any data guarantees. However, 
preserving redundancy in the face of highly dynamic membership is 
costly. We use a simple resource usage model to measured behavior from 
the Gnutella file-sharing network to argue that large-scale cooperative 
storage is limited by likely dynamics and cross-system bandwidth - not 
by local disk space. We examine some bandwidth optimization strategies 
like delayed response to failures, admission control, and load-shifting 
and find that they do not alter the basic problem. We conclude that when 
redundancy, data scale, and dynamics are all high, the needed 
cross-system bandwidth is unreasonable.

http://pmg.csail.mit.edu/~rodrigo/p2p-scl.pdf

regards,
Nazareno

Matthew Kaufman wrote:
> Alen Peacock:
> 
>>  I'd add: what is the self-interested motivation for a node 
>>to agree to cache the content in the first place? 
> 
> 
> This could be some external motivation like "I want anonymously-posted files
> about certain political views to be available for all to see" or "my
> corporate IT department says that we have to use this distributed
> collaboration tool"
> 
> 
>>If proactive caching were turned on by default in my p2p 
>>filesharing client, don't I have a very real incentive to 
>>turn this off in my own node to preserve bandwidth, disk 
>>space, and perhaps limit any legal liability? 
> 
> 
> In the general "filesharing" case? Absolutely. But that's not the only use
> for P2P technology or even P2P file transfer.
> 
> 
>>...which is similar to many of the arguments made against 
>>pre-fetching in traditional caching literature: how do you 
>>ensure that you prefetch the right content, especially when 
>>the cost of prefetching the wrong content is very high?
> 
> 
> Actually, if you're replicating content to other nodes in order to ensure
> availability or create more downloadable nodes in order to speed future
> downloaders, it is more like the RAID arguments than the cache arguments.
> 
> The real question is, IF you had a high-availability file sharing system,
> what files would you want to make available on it? (The answer is probably
> *not* the long tail of all files ever seen on generic file sharing services)
> 
> Matthew Kaufman
> matthew at matthew.at
> www.amicima.com
> 
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> 


-- 

Nazareno.

========================================
  Nazareno Andrade
  LSD - DSC/UFCG
  Campina Grande - Brazil
  http://lsd.dsc.ufcg.edu.br/~nazareno/

  OurGrid project
  http://www.ourgrid.org
========================================