[tahoe-dev] [tahoe-lafs] #393: mutable: implement MDMF

[tahoe-lafs]

#393: mutable: implement MDMF
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     Reporter:  warner        |       Owner:  kevan                                                                    
         Type:  enhancement   |      Status:  assigned                                                                 
     Priority:  major         |   Milestone:  1.9.0                                                                    
    Component:  code-mutable  |     Version:  1.0.0                                                                    
   Resolution:                |    Keywords:  newcaps performance random-access privacy gsoc mdmf mutable review-needed
Launchpad Bug:                |  
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Comment (by davidsarah):

 Replying to [comment:56 kevan]:
 >   - The way that you tell a mutable file whether it is SDMF or MDMF is
 poorly specified and kind of a kludge that I made a while ago to help me
 test things. It probably needs to be at least looked at, specified more
 precisely, and maybe changed. Right now, if you upload a mutable file that
 is larger than 128KiB, it is automatically made to be MDMF; otherwise, it
 is SDMF. These semantics are probably not what we want for backward
 compatibility/interoperating with older clients.

 We want to be able to test uploading of MDMF files, and enable their use
 on grids where all clients are known to be of a version that understands
 them, without breaking backward compatibility for grids with a mix of
 client versions.

 I can think of several ways to do that:
 1. Use a query parameter to webapi upload requests. This would default to
 SDMF in 1.9.0, and the default could be changed in some future version.
 2. Use a parameter in {{{tahoe.cfg}}}.
 3. A combination of 1 and 2, i.e. use a query parameter to the webapi
 request, with the default specified in {{{tahoe.cfg}}}.

 Option 1. is okay for testing, but then there's no obvious way to
 configure the WUI and CLI (or other frontends) to say that you only have
 newer clients and so want to use MDMF. That problem is solved by either 2.
 or 3.; the choice between them depends on whether we want to be able to
 specify this on a per-file basis.

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/393#comment:58>
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