Subject: Re: wedges and what does that mean?
To: Bill Studenmund <wrstuden@NetBSD.org>
From: David Laight <david@l8s.co.uk>
List: current-users
Date: 09/06/2006 00:05:49
On Tue, Sep 05, 2006 at 10:31:08AM -0700, Bill Studenmund wrote:
> 
> Well, with file handles you always have had the problem that the fsid may 
> change between boots. Now that file handles are opaque, things are a bit 
> harder, but something can still be done about it.

NFS assumes that file handles don't change across a server reboot.

Since, traditionally, the NFS file handle is a composite of the disk
major/minor, the inode and the inode generation number, if your file
system doesn't have a fixed dev_t or fixed inode numbers you are
somewhat stuffed.

I did some fixes to a layered FS to use semi-random values for these
because the client were accessing completely incorrect files after
a server reload.

Unfortunately if a server invalidates NFS file handles this way, the
clients tend to retry indefinitely - and without a time delay.
This doesn't do well for the network load!

	David

-- 
David Laight: david@l8s.co.uk