Re: Delays on "first" access to a NFS mount

[Olaf Kirch <olaf.kirch@oracle.com>]

On Thursday 08 March 2007 22:27, J. Bruce Fields wrote:
> There's some confusion here--the reason that this was happening was that
> we're mapping filehandles to exports by stat()ing the root of every
> exported filesystem.  That may be an obstacle to handling large numbers
> of exports, but it's not really related to the demand-loading question.

Sorry if I was expressing myself poorly. What I was driving at was that
it makes sense to not mount all file systems prior to starting the
NFS server.

> So why does demand-loading scale better?  Is the worry just the kernel
> memory required to store the export table for thousands of mostly
> inactive exports?

It means you can start serving files without having to wait for all 
file systems to be mounted (and having their journals replayed,
etc). All you need is a way for mountd to figure out whether a file system
is there already (so we can push the rootfh into the kernel) or whether it's
not (so nfsd can return EJUKEBOX or defer the request)

Olaf
-- 
Olaf Kirch  |  --- o --- Nous sommes du soleil we love when we play
okir@lst.de |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax

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