Path: utzoo!utgpu!news-server.csri.toronto.edu!utcs.toronto.edu!cks Newsgroups: comp.unix.wizards From: cks@hawkwind.utcs.toronto.edu (Chris Siebenmann) Subject: Re: (was slashes, now NFS devices) Message-ID: <1991Feb25.114204.5297@jarvis.csri.toronto.edu> Organization: Ziebmef home away from home References: <15236@smoke.brl.mil> <123382@uunet.UU.NET> <1991Feb22.141910.17013@decuac.dec.com> <14363@ulysses.att.com> Date: 25 Feb 91 16:42:04 GMT Lines: 35 ekrell@ulysses.att.com (Eduardo Krell) writes: | If you can access remote files, why can't you access remote devices using | the same mechanism? Under RFS, special files are interpreted by the server. For NFS, I can think of two reasons, one technological, one 'political': - NFS has no way of signalling when a device is opened or closed, or who is doing the opening or closing. Many character special devices and some block special devices have special semantics attached to opens and closes. There's also the issue of ioctl support, complete with byte order problems. - Sun didn't think it was necessary to support accessing remote devices in NFS, since it was seen as a replacement for Sun's ND, not as something that was supposed to be widely generic (cf. the first Usenix paper on NFS). One can construct remote filesystems where devices and symbolic links are handled on the server; RFS does at least devices 'right', and the V8/V9/V10 netb protocol does both right (except for ioctls between machines of different byte-sex/kernel ioctls). I have even heard of a way of doing diskless machines with either protocol; invent a new filesystem, one that's entirely in memory; then as part of the diskless client /etc/rc, create such a filesystem, mount it on /dev, and populate it. But NFS works, more or less, and is the de-facto standard at this point so we're stuck with it, botches and all. And the ease of crash recovery is nice (unlike some people, my machines don't run rcp.lockd). -- ported program: a program which takes constant or increasing effort to port to each new machine. portable program: a program which takes less effort to port to each new machine. cks@hawkwind.utcs.toronto.edu ...!{utgpu,utzoo,watmath}!utgpu!cks Brought to you by Super Global Mega Corp .com