[chord] chord meeting summary

[Benjie Chen]

here is a summary from this morning's chord meeting.

  - to address the issue that my application would like to do local
    caching, and it would be nice if the local cache part of lsd

    - we will add a local cache DB to lsd
    - this DB will store blocks, not fragments
    - blocks will not be replicated
    - apps will be able to access the DB (insert and retrieve)
    
    - we will support remote retrieval of data from this DB
      - add a RPC to retrieve block from the cache
      - for a regular retrieve that is looking for a fragment, we can
	optionally return a bit that indiciates if the entire block is
	in cache
    
    - i think this organization is cool. you can also
      - cache/store actual files in the cache db
      - store pointers in DHash; each pointer indicates the existance
	of a file in some lsd's local cache db

  - i heard something about bring back whole block storage and
    replication for small sized blocks.  if we can make it an option
    so an application can choose to always use whole block storage and
    replication, that'd be great.  alternatively, we can have tunable
    coding parameter so we can have the option to fragment a block in
    such a way that a smaller number of nodes is needed.

  - we decided that lazy/asynchronous replication is probably a good
    thing to support (again, triggered by a flag in the request). but
    i assume this will only happen when replication is once again
    implemented for small sized blocks.

  - we decided that admission control will be necessary for some apps.
    design/implement this later.

  - we decided there should be a proxy mode for lsd so it can just
    send requests through another lsd.
  
  - in an effort to maintain a sensible and structured location table,
    we will expand the "hint" interface between lsd and app, so an app
    can keep its own location cache and give guesses to the lsd. i
    think the big item here is to have lsd return list of successors
    to the app.

for now, i will be working on the separate cache DB w/ jsr.

-- 
benjie chen
benjie at lcs.mit.edu