[tahoe-lafs-trac-stream] [tahoe-lafs] #999: support multiple storage backends, including amazon s3

[tahoe-lafs]

#999: support multiple storage backends, including amazon s3
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     Reporter:  zooko         |      Owner:  zancas
         Type:  enhancement   |     Status:  new
     Priority:  major         |  Milestone:  soon
    Component:  code-storage  |    Version:  n/a
   Resolution:                |   Keywords:  gsoc backend s3
Launchpad Bug:                |
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Comment (by davidsarah):

 Review of [attachment:backends-configuration-docs.darcs.patch]:

 ``s3.rst``:
 * Add a short introduction saying what S3 is and why anyone might want to
 use it.

 * It's a bit inconsistent that the value of the backend option is
 uppercase "S3", but the other option names are lowercase "s3_*". Also, I
 would make it "s3.*", since that's similar to the use of "." to group
 other related options.

 * Should the ``s3_url`` option include the scheme name, i.e. defaulting to
 ``http://s3.amazonaws.com`` ? We might want to support https in future
 (although there would be more to configure if we check certificates).

 * In the description of ``s3_max_space``, copy the paragraph starting
 "This string contains a number" from ``disk.rst`` rather than referring to
 it.

 * {{{"enabling ``s3_max_space`` causes an extra S3 usage query to be sent
 for each share upload, causing the upload process to run slightly slower
 and incur more S3 request charges."}}}

   Each space query could be amortized over several uploads, using an
 estimate of the used space in-between. (That wouldn't be accurate if there
 are several storage servers accessing the same bucket, but it would be
 accurate enough if the maximum number of such servers is limited.) Even if
 we don't implement that right away, I'm not sure that this performance
 issue needs to go in ``s3.rst``.

 ``disk.rst``:
 * "Storing Shares in local filesystem" -> "Storing Shares on a Local
 Filesystem"

 * use ``backend = disk``, and say that it is the default.

 ``configuration.rst``:
 * "Clients will be unaware of what backend is used by the server." ->
 "Clients need not be aware of which backend is used by a server."

 * "including how to limit the space that will be consumed" -> "including
 how to reserve a minimum amount of free space"

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/999#comment:26>
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