#1793 closed enhancement (fixed)

Clarified risks of shares.happy <= shares.needed in configuration.rst

Reported by: Sagi Owned by: marlowe
Priority: minor Milestone: undecided
Component: documentation Version: 1.9.2
Keywords: preservation, docs Cc:
Launchpad Bug:

Description

< Sagi> suppose I currently have 3 nodes online. When I set N=6,K=H=3, every
        node gets two shares. Now if one fails, I still have my data
< Sagi> in addition, one of the shares on the remaining two can get corrupted.
< zooko> Sagi: right.
< Sagi> configuration.rst says "A value of shares.happy <= k is allowed, but
        does not provide any redundancy if some servers fail or lose shares."
< Sagi> that is incorrect for this situation, then.
< Sagi> I think that sentence is only correct when gridsize >= N
< zooko> Sagi, I believe you are exactly correct.

Attachments (1)

0001-Clarified-risks-of-shares.happy-k-in-docs.patch (879 bytes) - added by Sagi at 2012-07-12T19:38:23Z.

Download all attachments as: .zip

Change History (6)

comment:1 Changed at 2012-07-12T19:39:26Z by Sagi

  • Summary changed from Clarified risks of shares.happy - shares.needed in configuration.rst to Clarified risks of shares.happy <= shares.needed in configuration.rst

comment:2 Changed at 2012-07-12T19:47:43Z by davidsarah

So, if shares.happy <= k, whether there is any redundancy depends on the share distribution. It is not the case in general that for N=6, k=H=3, each server is guaranteed to have 2 shares initially. That's what will happen if everything is working correctly (all servers have free space, no failures during upload), but the upload can still succeed without that being true.

comment:3 Changed at 2012-07-12T20:31:04Z by david-sarah@…

  • Resolution set to fixed
  • Status changed from new to closed

In 9a6fb895459b3b93:

docs/configuration.rst: clarify statement about lack of redundancy when shares.happy <= k. fixes #1793

comment:4 Changed at 2012-07-16T00:43:13Z by david-sarah <david-sarah@…>

In 9a6fb895459b3b93:

docs/configuration.rst: clarify statement about lack of redundancy when shares.happy <= k. fixes #1793

comment:5 Changed at 2012-07-20T03:55:01Z by david-sarah@…

In 5930/cloud-backend:

[rebased for cloud-backend] docs/configuration.rst: clarify statement about lack of redundancy when shares.happy <= k. fixes #1793

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