[Lustre-devel] OST pool administration (was RE: Stripe offset default)

[Peter Braam]

On 24 November 2010 06:31, Eric Barton <eeb at whamcloud.com> wrote:

> Peter,
>
> > The  proposal for acl / Group / users violates Posix, and may lead
> > to results users don't expect.  Sgid directories and inheritance
> > on ACLs are safer I think.
>
> This should probably be in a separate thread since I was trying to make
> a case for improving the administration storage pools (the classic
> gold/silver/bronze scenarios) which is really different from the default
> file layout issue.
>
> If the default layout in a directory creates files in the "gold" OST
> pool but the user has no permissions for that pool, then returning
> EPERM on file creation would potentially be inconsistent with the
> permissions on the directory itself.  Is this what you meant by being
> inconsistent with Posix?  If so, I'm afraid I don't follow the point
> about sgid.
>
>
Group writeable directories with the sgid mode bit set, exceptionally
inherit permissions from the parent directory upon creation of new
subdirectories (assuming no explicit mode is passed).   So it automatically
descends down the tree, just like the striping attributes do.  I believe
POSIX ACLs have a similar inheritance option.

I have sympathy for the idea btw, but basic permission issues failing
because of it is something that needs some thought.



> I guess using per-pool quotas rather than permissions might be more
> natural.  I'd be interested to hear people's opinions...
>


That makes sense also, and perhaps 0 quota could be interpreted as a denial
to create also, without causing harm.

Peter


>
>          Cheers,
>                   Eric
>
>
>
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