Re: [ANNOUNCE] DualFS: File System with Meta-data and Data Separation

Juan Piernas Canovas
2007-02-15T23:02:03Z

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Hi Jörn,

On Thu, 15 Feb 2007, [utf-8] Jörn Engel wrote:

> On Thu, 15 February 2007 19:38:14 +0100, Juan Piernas Canovas wrote:
>>
>> The patch for 2.6.11 is not still stable enough to be released. Be patient
>> ;-)
>
> While I don't want to discourage you, this is about the point in
> development where most log structured filesystems stopped. Doing a
> little web research, you will notice those todo-lists with "cleaner"
> being the top item for...years!
>
> Getting that one to work robustly is _very_ hard work and just today
> I've noticed that mine was not as robust as I would have liked to think.
> Also, you may note that by updating to newer kernels, the VM writeout
> policies can change and impact your cleaner. To an extent even that you
> had a rock-solid filesystem with 2.6.18 and thing crumble between your
> fingers in 2.6.19 or later.
>
> If the latter happens, most likely the VM is not to blame, it just
> proved that your cleaner is still getting some corner-cases wrong and
> needs more work. There goes another week of debugging. :(
>
> Jörn
>
Actually, the version of DualFS for Linux 2.4.19 implements a cleaner. In
our case, the cleaner is not really a problem because there is not too
much to clean (the meta-data device only contains meta-data blocks which
are 5-6% of the file system blocks; you do not have to move data blocks).

Anyway, thank you for warning me ;-)

Regards,

Juan.

--
D. Juan Piernas Cánovas
Departamento de Ingeniería y Tecnología de Computadores
Facultad de Informática. Universidad de Murcia
Campus de Espinardo - 30080 Murcia (SPAIN)
Tel.: +34968367657 Fax: +34968364151
email: piernas@ditec.um.es
PGP public key:
http://pgp.rediris.es:11371/pks/lookup?search=piernas%40ditec.um.es&op=index

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