Announcing Fedora Activity Day - Fedora Development Cycle 2009

[Matthew Woehlke]

Michael Cronenworth wrote:
> Matthew Woehlke wrote:
>> What about dropping hierarchical mirroring altogether? Why hasn't
>> someone developed a distributed (i.e. bittorrent-like) system for mass
>> mirroring? :-)
>>
> 
> Already discussed[1][2] on the fedora-test-list.
> 
> [1] https://www.redhat.com/archives/fedora-test-list/2009-June/msg00032.html
> [2] https://www.redhat.com/archives/fedora-test-list/2009-June/msg00062.html

It's too bad fedora-test-list doesn't seem to be on gmane (or isn't 
named obviously; gmane.org is being too slow for me to ask about the 
mail address).

In an idealized network (all servers have roughly the same speed links 
to all other servers), BT distribution should get everything to everyone 
in about 2x as long as to send everything to one server. In the worst 
case, it should take 2x as long as to send everything over the slowest 
link in the mesh, which if only care about when /all/ mirrors are fully 
synced (a very reasonable assumption in this type of scenario) is still 
pretty close to being an unconditional improvement. In practice, the 
actual result will be somewhere between 2x the time to transfer over the 
fastest link, and over the slowest link.

In a generalized sense, the time-order to distribute via bittorrent in 
an idealized network is O(2 * K), where hierarchical systems are, at 
best I believe O(log(base N) K) for the furthest mirrors, and still O(N0 
* K) for the tier-0 mirrors. That's an improvement of an entire order 
(O(log n) -> O(n)).

The point about there not being tools currently is what would need to be 
addressed.

-- 
Matthew
Please do not quote my e-mail address unobfuscated in message bodies.
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