[tahoe-dev] How many servers can fail? (was: Tahoe-LAFS Logo selection)

[Dirk Loss]

On 25.10.11 15:28, David-Sarah Hopwood wrote:
> On 25/10/11 11:23, Dirk Loss wrote:
>> I got my false impression from the following sentence in
>> http://tahoe-lafs.org/trac/tahoe-lafs/browser/trunk/docs/about.rst
>> "Therefore only the simultaneous failure of N-K+1 (with the defaults, 8)
>> servers can make the data unavailable."
> 
> Fixed: http://tahoe-lafs.org/trac/tahoe-lafs/changeset/5338/trunk/

Thank you. That was very helpful. Here's the text again:

"The ciphertext is erasure-coded into N shares distributed across at
least H distinct storage servers (the default value for N is 10 and for
H is 7) so that it can be recovered from any K of these servers (the
default value of K is 3). Therefore only the failure of H-K+1 (with the
defaults, 5) servers can make the data unavailable."

To foster my understanding, I've tried to visualize what that means:

 http://dirk-loss.de/tahoe-lafs_nhk-defaults.png

Is that interpretation correct?

Best regards
Dirk