[tahoe-dev] a note on nomenclature (was: newbie questions)

zooko zooko at zooko.com
Fri Sep 19 21:56:53 UTC 2008


On Sep 19, 2008, at 14:29 PM, Brian Warner wrote:

>> 1/ Is it possible to specify that we have N servers and want
>> tolerance to K failure ? Or to know the state of redundancy ?
>
> FYI: in our nomenclature (which is reasonably close to the standard  
> usage)
> "N" is the number of shares created, and "k" is the number of  
> shares you
> need.

Yes, this is becoming the new standard terminology.  Here is an  
excerpt from James Plank's latest paper (I am a co-author):

"""
It is an unfortunate consequence of the history of erasure coding  
research that there is no unified nomenclature for erasure coding. We  
borrow terminology mostly from Hafner et al [13], but try to conform  
to more classic coding terminology (e.g. [5, 19]) when
appropriate. Our storage system is composed of an array of n disks,  
each of which is the same size. Of these n disks, k of them hold data  
and the remaining m hold coding information, often termed parity,  
which is calculated from the data.
"""

Regards,

Zooko
---
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