Re: [Gluster-devel] Request for "read-only" translator

[Raghavendra G]

Hi Steffen,
Please find the answers inlined.

On 6/28/07, Steffen Grunewald <address@hidden > wrote:
> With glusterfs 1.3 getting close to a releasable state, I started thinking
>
> about the structure of a global namespace for our applications.
> There will be "mirrored machines" (AFR) for crucial data, and there should
> be part of the servers offering read-only stuff (making sure nothing gets
> added to the filesystem) perhaps also on top of an AFR layer (for the
> super important, time critical input data repositories).
> This results in the following structure (with individual "units" in
> varying
> counts):
>
> brick1a
>       > AFR (mirror) > readonly
> brick1b                          \
>                                  |
> brick2a                          |
>       > AFR (mirror) > readonly  |
> brick2b                           > unify
>                                  |
> brick3 (AFR if I'm paranoid)     |
> brick4 (can be AFR)              |
> brick5 (can be AFR)              /
> ...
>
> (Apologies for the ASCII graphics.)
>
> Bricks 1 and 2 (which come in two copies) would store the "never lose
> this"
> stuff while it's still possible to work (store new data) on the other
> bricks.
>
> Of course, two features are essential for such a setup:
> - a "readonly" xlator (does the "filter" xlator yield this? couldn't find
>         anything about "option" syntax)


Yes.  "Filter" xlator gives the read-only functionality. And it accepts no
options.

- a "unify" xlator which can handle read-only subvolumes (can it already?
>         does this have an influence on the choice for schedulers?)


There should be no problem with  unify handling read-only subvolumes.

Is there someone who already implemented this to some extent and is willing
> to share her/his config? Any suggestions which scheduler to choose?
>
> Cheers,
> Steffen
>
> --
> Steffen Grunewald * MPI Grav.Phys.(AEI) * Am Mühlenberg 1, D-14476 Potsdam
> Cluster Admin * http://pandora.aei.mpg.de/merlin/ * http://www.aei.mpg.de/
> * e-mail: steffen.grunewald(*)aei.mpg.de * +49-331-567-{fon:7233,fax:7298}
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>
>
>
>
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regards,
--
Raghavendra G