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Message-ID: <3e1162e60510021520t787e23e1nf74b5f2e6180a2e7@mail.gmail.com>
Date: Sun, 2 Oct 2005 15:20:06 -0700
From: David Leimbach <leimy2k@gmail.com>
Reply-To: David Leimbach <leimy2k@gmail.com>
To: jonathan@jonmasters.org
Subject: Re: Linux gains lossless filesystem
Cc: Tiesto Tijs <t.tijs@freemail.hu>, linux-kernel@vger.kernel.org
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On 10/2/05, Jon Masters <jonmasters@gmail.com> wrote:
> On 9/30/05, Tiesto Tijs <t.tijs@freemail.hu> wrote:
>
> > i would like to know, what is your opinion about this
> > filesystem:
>
> > http://www.linuxdevices.com/news/NS9521569196.html
>
> Why wasn't it possible to make device mapper do what they wanted in
> combination with modifying the journalling behaviour of an existing
> fs?

I believe it may be possible, if it's not been done already, to use
the venti block archival system from Plan 9 [it's in userspace and has
been ported to linux] as well as the fossil filesystem [also in
userspace] to achieve a lossless file system configuration.  Also,
since it is served over 9P, it could be done for a remote filesystem
on a diskless node potentially.

What you end up with is a WORM device served up by Venti [which is
made efficient storagewise by coalescing like blocks and hashing them
with SHA1] and keeping a "current snapshot" served up over 9P using
Fossil.  That's how my Plan 9 box is currently configured anyway.

I think with v9fs and plan9ports you could configure something like
this though I don't know if anyone has done it yet.

If anyone is interested in how Venti scales here is a paper with
pretty graphs collecting the data of an almost 10 year usage period of
this technology at Bell Labs.
http://www.cs.bell-labs.com/sys/doc/venti/venti.html

Dave

>
> Jon.
> -
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