[Lustre-devel] Recovering opens by reconstruction

Nicolas Williams Nicolas.Williams at sun.com
Fri Jul 3 17:48:51 PDT 2009

On Fri, Jul 03, 2009 at 04:55:28PM -0500, Nicolas Williams wrote:
> On Fri, Jul 03, 2009 at 11:02:16PM +0400, Mikhail Pershin wrote:
> > On Fri, 03 Jul 2009 02:39:45 +0400, Nicolas Williams  
> > <Nicolas.Williams at sun.com> wrote:
> > >We're working on adding replay RPC signatures, so that clients may only
> > >replay RPCs that have been seen by the server (thus signed).
> > 
> > Could you explain that more? All replays have been seen by server just by  
> > definition because client got reply from server, so what is purpose of  
> > such signing?
> They've been seen, indeed, but when replayed not all the same
> permissions checks may be done, so the server needs to know that the
> replay is safe to process.  There's two ways to do that: never skip any
> permissions checks when processing replayed RPCs, or have the server
> sign replayable RPCs so the server can know validate any replays.  I've
> not looked at a complete list of checks that are skipped on replays --
> perhaps we should have such a list before we go down the replay
> signature path.

Oh, I forgot for a moment, but the other point of replay signatures is
to prevent clients from causing other clients to be evicted.

More information about the lustre-devel mailing list