[tahoe-dev] Kragen Sitaker, Brian Warner, Josh Wilcox, Bram Cohen, Russ Roberts, and Nassim Taleb on erasure coding probabilities

zooko zooko at zooko.com
Sat Sep 29 17:39:25 UTC 2007


On Sep 26, 2007, at 2:00 PM, Arno Waschk wrote:

> is it possible that Bram means something like "<0.95 means that human
> beings are using the power switch, so you would (a) need to analyze  
> human
> psychotics and (b) might see correlated failures when many people are
> switching off during the same baseball event?"

That's a good theory.  I think that's a good way to categorize nodes  
by availability.

We can separately analyze "availability" -- whether the file is  
available right when you want it -- from "reliability" -- whether the  
file will become available eventually.

For example, suppose you have a friendnet for sharing backup space.   
The availability of nodes might be low -- especially if the friends  
don't have always-on computer and always-on internet connections.

But the reliability ought to be pretty high -- your friends won't  
delete your data unless there is some kind of accident such as a  
mistake on their part or a hard drive crash.

Regards,

Zooko




More information about the tahoe-dev mailing list