[Lustre-devel] Stripe offset default

Peter Braam peter_braam at xyratex.com
Tue Nov 23 12:50:02 PST 2010


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.

Peter

Sent from my iPad

On Nov 23, 2010, at 10:20, "Eric Barton" <eeb at whamcloud.com> wrote:

> 
> Nick Cardo at NERSC mentioned at the LUG, and again when I chatted
> with him at SC10, that setting the default stripe offset is positively
> dangerous.  I think he has a point.
> 
> Setting file layout precisely can be essential for applications that
> know precisely what they're doing and want to control how aggregate
> OST load is balanced.  But the default file layout is another matter
> entirely.  Setting the default to a fixed layout, or even just a fixed
> starting OST has got to be the most direct path to achieving OST load
> imbalance.
> 
> I believe, now that lfs setstripe uses options rather than positional
> parameters, that the risk of unintentional errors is much less.  But
> that still leaves the filesystem vulnerable to naïve or malicious
> users.  So I propose that we should continue to check permissions
> normally when setting the default stripe _count_, but restrict the
> ability to set a specific default stripe _offset_ to the superuser.
> 
> Thoughts?
> 
> P.S. Do people also agree that setting user/group/ACL permissions on
> OST pools would be a Good Thing?
> 
>          Cheers,
>                   Eric
> 
> Eric Barton
> CTO Whamcloud, Inc.
> 
> 
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