Re: fsid.major/minor

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From: Brian Pawlowski (beepy@netapp.com)
Date: 03/19/99-06:48:29 PM Z


From: beepy@netapp.com (Brian Pawlowski)
Message-Id: <199903200048.QAA00031@turok.netapp.com>
Subject: Re: fsid.major/minor
Date: Fri, 19 Mar 1999 16:48:29 -0800 (PST)

Yeah, but what a "file system" is from a client's perspective
has always been a strained concept.

Obviously we are able to propagate the space allocation information
contained in a qtree - which works out just dandy.  But a "qtree"
is not quite a "filesystem" - though it has several properties that one
would typically consider those of a file system.

It escapes me now what the NFS->AFS gateway did in the AFS product.
Basically an AFS client acted as an NFS->AFS translator (and authentication
proxy) allowing NFS clients to "mount" the *entire* AFS cell.  Now,
that cell could consist of many file *servers* never mind file systems,
yet the user was unaware (other than from a performance perspective).

Perhaps we should consider letting go of our preconceptions (or
prejudices) of what a file system is supposed to be, along with
letting go of our dogmas like "statelessness" - and just look for
solutions that support or enhance current practice?

beepy

> Dave Hitz writes:
> > Things would actually be a little better if the client would send over
> > the FH you actually specified in the statfs() system call, rather than
> > the FH for the mount point, because the way it is now, you cannot find
> > the usage of the q-tree unless the mount point is inside the q-tree.
> > It would be nicer if you could actually mount the root of the server,
> > and then get "df" information based on the directory you pass in.
> 
> Yes, this is a bit annoying.  It goes to the mounted root because
> the statfs() system call is implemented as as a filesystem operation:
> VFS_STATVFS() rather than a vnode operation, e.g. VOP_STATVFS().
> 
> There's an implicit assumption in Solaris (and I'm sure other 
> UNIX clients) that the amount of space available is invariant
> over a mounted filesystem, i.e. doesn't change from directory
> to directory within a filesystem.
> 
> 	Brent


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