Re: [Vrs-development] Distributed Filesystem

[Chris Smith]

Elequently put
10/10 and a gold star.

Chris

On Thursday 11 July 2002 21:48, Eric Altendorf wrote:
> On Wednesday 10 July 2002 20:47, Ian Fung wrote:
> > first question is whether the vrs is going to house a distributed
> > file *system*? or a distributed file *repository*?
>
> What they want is a distributed file *system*.
>
> > distributed file repository doesnt have the same properties as a
> > dfs. a file system needs to be consistent and sychronized.
>
> The goals are as follows:
>
> * Guaranteed consistency, synchronization, etc. -- in short it must
>       guarantee standard Unix filesystem semantics
> * Duplication of data -- each block of data must be duplicated on
>       multiple hosts, in case one or more hosts goes offline.
> * Splitting up of data -- it should be possible to require that a
>       file is never completely stored on a single host (or, more
>       generally, that no more than XX% of a file is ever stored
>       on a single host)
> * Encryption -- all data must be encrypted
> * Dynamically balanced -- hosts should be able to go on and offline
>       at will; when hosts go offline the remain hosts should re-
>       balance the distribution of the data blocks; when hosts come
>       online the data must be synchronized.
> * Efficiency (a nicety) -- hosts should try to store the data they
>       personally need, to cut down on network traffic, etc.
>
> > it is impossible to create a file system by the
> > traditional definition in a distributed environment. what we can do
> > is try to maintain consistency and sychronization as best we can.
>
> Not exactly.  It is possible to guarantee consistency and
> synchronization.  It is possible to guarantee standard Unix
> filesystem semantics despite the highly dynamic and unreliable
> hardware base.  It's just very difficult (nobody else has ever done
> this, to my knowledge -- the closest I think that currently exists
> would be distributed database servers), and may result in very poor
> performance in some situations.
>
> All hardware is intrinsically unreliable; the science of writing
> reliable software on unreliable hardware is the science of
> transaction processing.  The proposed distributed filesystem is
> possible; but I think it is probably too ambitious at this stage of
> the project.
>
> That's my take on it....
>
> Eric
>
> --
> "First they ignore you.  Then they laugh at you.
>  Then they fight you.  And then you win."             -Gandhi
>
>
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-- 
Chris Smith
  Technical Architect - netFluid Technology Ltd.
  "Internet Technologies, Distributed Systems and Tuxedo Consultancy"
  E: address@hidden  W: http://www.nfluid.co.uk