Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!husc6!rice!sun-spots-request From: hedrick@geneva.rutgers.edu (Charles Hedrick) Newsgroups: comp.sys.sun Subject: Re: Are fileservers a waste of money Keywords: Hardware Message-ID: Date: 10 May 89 06:14:50 GMT References: <550@trlamct.oz> Sender: usenet@rice.edu Organization: Rutgers Univ., New Brunswick, N.J. Lines: 56 Approved: Sun-Spots@rice.edu Original-Date: 4 May 89 23:23:14 GMT X-Sun-Spots-Digest: Volume 7, Issue 280, message 3 of 18 I don't think anybody really has a complete answer to this question. However I have at least some informed comments. First, fileservers in general may or may not be a waste of money, but *your* fileserver seems to be. You have a 3/260 with a XY451 controller. Our results (which agree with Sun's configuration guide, by the way) suggest that a 3/260 isn't all that much faster than a 3/160 when used as a file server. (It's a dandy machine for real computing though.) Furthermore, it is being crippled by the XY451. You'd almost certainly get better throughput from one of the 3rd party fast SCSI disks on a 3/60 than from this file server, and at a fraction of the cost. Both Sun and other tests agree that the Sun shoebox is similar to network access to an unloaded file server. Sun originally (back when the 3/50 first came out) said that both were about 1/2 the speed of a "real" SMD disk. However SCSI technology has improved since those tests. (Those were the days of the XY451 and Eagles.) It appears that with good embedded SCSI disk controllers you can now get almost as good results out of local SCSI disks as SMD (indeed some results suggest better, but they tend to be comparing with less than optimal SMD controllers), at least in single-user configurations. In the worst case, it seems that swapping from a file server is a disaster. The worst case assumes - that all of your clients are swapping their hearts out at the same time - that you're comparing to local swapping disks using the best SCSI technology, and not the old Sun shoeboxes - that you have no more I/O bandwidth in your file server than on a client. In that case, 6 clients are going to see less than 1/6 the swapping performance they would see if they had local disks. However, you may not have that worst case. Here are things which may combine to make a file server reasonable: - your clients may not all need to swap at the same time. If they are using Lisp, this means you've put lots of memory in them. Note that this strategy has to be used on all your machines. If you have a couple of machines without enough memory, then they may swap continuously. In that case they'll degrade even machines that have enough memory. Enough memory means enough to keep the swap rate down, not to totally eliminate swapping. Even the 12M machine will need to swap now and then, and when it does, it will get killed by the 4M machines. - you may be able to afford more I/O throughput on the server than on an individual client. E.g. you may be able to use more disks in parallel, or more memory as a cache (both on the controller and in main memory). You'd certainly do better with one of the new generation of SMD controllers, particularly if you're running a release of SunOS that doesn't do overlapped seek on the Xylogics controllers. At the moment we are still using 3/50's and 3/60's in diskless configurations. However all of the proposals I've made so far for Sparcstation 1's have involved local 100MB disks.