Changes between Version 10 and Version 11 of GSoCIdeas


Ignore:
Timestamp:
2013-04-11T05:42:56Z (11 years ago)
Author:
zooko
Comment:

Upload Strategy of Happiness

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  • GSoCIdeas

    v10 v11  
    1515
    1616||''Project''||''Tickets''||''Difficulty''||
    17 ||[#ShareRebalancingandRepair Share rebalancing and repair]||#699,#232||tricky||
     17||[#ShareRebalancingandRepair Share rebalancing and repair]||#699, #232||tricky||
     18||[#UploadStrategyOfHappiness Upload Strategy Of Happiness]||##610, #1124, #1130, #1293, #1382, #1814||tricky||
    1819
    19 ... to be filled in...
    2020
    2121== Share Rebalancing and Repair ==
    2222
    23 Tahoe-LAFS is not as robust with regards to lost or corrupted shares as it could be.  In part, this is because the repair functionality is limited in its efforts to spread shares out among new servers or servers which did not previously hold a given share (#699, #1130).  In addition, mutable files do not spread out to new servers upon modification (#232).  The servers-of-happiness metric is also not uniformly applied, with some operations succeeding even though an entity is not happy ([https://tahoe-lafs.org/trac/tahoe-lafs/query?status=!closed&keywords=~servers-of-happiness&order=priority bugs]).
     23Tahoe-LAFS is not as robust with regards to lost or corrupted shares as it could be.  In part, this is because the repair functionality is limited in its efforts to spread shares out among new servers or servers which did not previously hold a given share (#699).  In addition, mutable files do not spread out to new servers upon modification (#232).
    2424
    2525A Summer of Code project might tackle repair and rebalancing, ensuring that servers-of-happiness is met whenever possible on any upload, repair, or mutable modification.  The notes on ServerSelection and related configurations may also be relevant here.
     26
     27== Upload Strategy Of Happiness ==
     28
     29The ''Servers of Happiness'' criterion is already in place for deciding whether a given distribution of shares over servers satisfies the user's requirements for fault-tolerant distribution. However, the algorithm that decides what shares to upload to which servers is not optimized to always satisfy the Servers of Happiness criterion. [https://zooko.com/uri/URI%3ADIR2-RO%3Aoljrwy5i2t3dhcx5mzrksegehe%3Axtac4ubcnr5eqo6d7h4wyj5sm522olj4mthizz2i3lfw2b5nla6q/Latest/compsci/Carstensen-2011-Robust_Resource_Allocation_In_Distributed_Filesystem.pdf Kevan Carstensen's master's thesis] explains the context in great details and proposes an ''Upload Strategy of Happiness'' algorithm for allocating shares to servers. Implementing the ''Upload Strategy of Happiness'' should close the following tickets: #610, #1124, #1130, #1293, #1382, #1814.