milne@ICS.UCI.EDU (Alastair Milne ) (02/02/90)
Since our installation had been using RARP for booting PC-NFS for quite a while, and eventually had to give it up, I thought it might be of interest for others to hear what happened. When we first installed PC-NFS (v 3.0) we tried to have it use RARP, and we thought we were reasonably successful (once we got past problems with interrupt numbers). The PC's would boot to the net, though they were pretty laggardly about it. I believe the Sun's that could volunteer PC-NFSD service are all Sun 3's, so perhaps we were simply putting up with not having Sun 4's. However, we found that the frequency of successful booting was going down. We were used to PC's hanging during booting from time to time, and having to be re-booted after 3 minutes or so of apparently waiting for something from the net which was never coming -- but it was getting to be that you would expect to have to boot a machine 2 or 3 times before the net was properly up. Unfortunately, the details surrounding this are a bit hard to keep straight, so the description is not as clear as I'd like. We updated to 3.0.1 at one point, and I thought performance was improving, but ultimately the failure frequency just kept going up. We were also moved off the backbone of the department's net to a subnet from our PC-NFSD server. This should have improved performance, since the backbone was getting busier and busier, but it didn't solve anything. Finally our network services manager told me he'd been looking at how PC-NFS boots and what PC-NFSD does for it, and told me that he thought the RARP request was asking, not for a YP server directly, but for any respondent to tell it what that machine's YP server was, and the booting PC would then try to use that server too. Since a fair number of YP servers are available which don't serve our subnet, but could well serve any recipient of our RARP broadcast packets, it was quite likely we'd wind up requesting a server that couldn't service us. So he suggested discarding RARP, and giving each PC its own little host table instead. So I did that, including only the PC's own name and IP number, and those of a couple of available servers -- including the PC-NFSD server, of course. That lets the PC boot to the net just about as fast as the server will respond. Then I issue a NET YPDOMAIN xxxx and a NET YPSET *, and we have back Yellow Pages. Note that, as far as I know, all information but what's in HOSTS is still obtained from the net, including the subnet mask. This arrangement has been doing us fine. All the PC's boot the net much faster than they ever did before. My only regret is that if there are any more addressing changes, I'll have to revise at least 8 host tables by hand. Our site has been through at least 3 address changes so far, and RARP has saved me from having to lift a finger for them. But I can't deny booting performance without it has been much better. Anybody else had this kind of luck with RARP? Alastair Milne, U.Calif. Irvine