Changes between Initial Version and Version 3 of Ticket #869


Ignore:
Timestamp:
2010-03-25T00:10:17Z (11 years ago)
Author:
davidsarah
Comment:

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  • Ticket #869

    • Property Summary changed from Allow Tahoe filesystem to be run over a different grid/DHT implementation to Allow Tahoe filesystem to be run over a different key-value-store / DHT implementation
  • Ticket #869 – Description

    initial v3  
    1 source:docs/architecture.txt describes Tahoe as comprising three layers: '''grid''', '''filesystem''', and '''application'''.
     1source:docs/architecture.txt describes Tahoe as comprising three layers: '''key-value store''', '''filesystem''', and '''application'''.
    22
    3 Most of what makes Tahoe different from other systems is in the filesystem layer -- the layer that implements a cryptographic capability filesystem. The grid layer implements a Distributed Hash Table, which is a fairly well-understood primitive with many implementations. The Tahoe filesystem and applications could in principle run on a different DHT, and it would still behave like Tahoe -- with different (perhaps better, depending on the DHT) scalability, performance, and availability properties, but with confidentiality and integrity ensured by Tahoe without relying on the DHT severs.
     3Most of what makes Tahoe different from other systems is in the filesystem layer -- the layer that implements a cryptographic capability filesystem. The key-value store layer implements (a little bit more than) a Distributed Hash Table, which is a fairly well-understood primitive with many implementations. The Tahoe filesystem and applications could in principle run on a different DHT, and it would still behave like Tahoe -- with different (perhaps better, depending on the DHT) scalability, performance, and availability properties, but with confidentiality and integrity ensured by Tahoe without relying on the DHT severs.
    44
    55However, there are some obstacles to running the Tahoe filesystem layer on another DHT:
    66 * the code isn't strictly factored into layers (even though most code files belong mainly to one layer), so there isn't a narrow API between the grid and filesystem-related abstractions.
    77 * the communication with servers currently needs to be encrypted (independently of the share encryption), and other DHTs probably wouldn't support that.
    8  * because the filesystem has only been used with one grid layer up to now, it may make assumptions about that layer that haven't been clearly documented.
     8 * because the filesystem has only been used with one key-value store layer up to now, it may make assumptions about that layer that haven't been clearly documented.
    99
    1010Note that even if the Tahoe code was strictly layered, we should still expect there to be some significant effort to port Tahoe to a particular DHT. The DHT servers would probably have to run some Tahoe code in order to verify shares, for example.