From owner-freebsd-hackers Sun Dec 5 15:11: 7 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from mail.rpi.edu (mail.rpi.edu [128.113.100.7]) by hub.freebsd.org (Postfix) with ESMTP id 6480314C2F for ; Sun, 5 Dec 1999 15:11:04 -0800 (PST) (envelope-from drosih@rpi.edu) Received: from [128.113.24.47] (gilead.acs.rpi.edu [128.113.24.47]) by mail.rpi.edu (8.9.3/8.9.3) with ESMTP id SAA86846; Sun, 5 Dec 1999 18:07:06 -0500 Mime-Version: 1.0 X-Sender: drosih@mail.rpi.edu Message-Id: In-Reply-To: References: Date: Sun, 5 Dec 1999 18:12:51 -0500 To: Robert Watson , Assar Westerlund From: Garance A Drosihn Subject: Re: Portable way to compare struct stat's? Cc: Wes Peters , Randell Jesup , freebsd-hackers@FreeBSD.ORG Content-Type: text/plain; charset="us-ascii" ; format="flowed" Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG At 3:17 PM -0500 12/4/99, Robert Watson wrote: >On 4 Dec 1999, Assar Westerlund wrote: > > > Garance A Drosihn writes: > > > In the case of AFS, I think you'd want to expand the size of st_dev. > > > All files in an AFS volume are "one device", I would think. If the > > > "device" is gone (ie, the volume is not mounted), then all files in > > > that "device" (volume) will not be available. > > > > I'm confused. Did you mean `st_ino' there? I agree that you want to > > see the whole AFS space as a single device. > >I agree. Well, I'm happy to have it that way if everyone prefers that, but I really did mean to suggest that each AFS volume would be a separate device. Not "all of AFS" as one device, or even "all of one AFS cell" as one device. Do we have one device for "all NFS filesystems from all hosts"? (my assumption is "no", but maybe I'm wrong (*)). In local filesystems, a device is a partition on one hard disk. That one partition could be unavailable (ie, "not mounted"), in which case all files in that partition are not available. In AFS, the "mountable quantity" is a volume. You can mount the same volume in multiple places in AFS-land, in fact. If there's an AFS problem, you can be in a situation where "most" of an AFS cell is up, but particular volumes are not available because they are being salvaged. To me, all of this seems to indicate that AFS volumes are pretty analogous to what are used for devices on a local file system. But really, any way we could arrange it would be fine with me... (*) - I'm told that SGI's claim that all mounts (except lofs) will have a unique st_dev, including NFS mounts. On the other hand, I'm also told that linux seems to use the same st_dev value for all NFS mounts from a given host. In my mind, the linux behavior would suggest one st_dev value per AFS cell... --- Garance Alistair Drosehn = gad@eclipse.acs.rpi.edu Senior Systems Programmer or drosih@rpi.edu Rensselaer Polytechnic Institute To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message