pcl@robots.oxford.ac.uk (Paul Leyland) (12/10/88)
I would welcome advice, thoughts and opinions on the following problem. How do we upgrade a small-to-medium size system into a medium-to-large size one? At present, we have a network of 10 diskless Sun-3's (mostly 3/50's) and 5 diskful machines: a 4/260C, three 3/160C's and a 3/180S file server. The 3/180 provides root, pub and swap space for all the diskless machines; the diskful machines provide local swap and SunOS, but mount users filesystems and local system software from the server. The 3/160's have 140Mb SCSI disks; the 4/260 has a 560Mb SMD disk; the 3/180 has two Eagles on a 451 controller and a 1.4Gb NEC disk on an Interphase 4400 controller. The server is also used for tape backups, printing, mail, gatewaying to the campus ethernet and so on. Direct logins on it are strongly discouraged so to give more performance for the rest of the net. In the next few months, we will be getting several diskless 4/100's and a couple of diskful Sun-4's. All of this lot will add to the load on the ethernet (currently running at about 25% loading within factor two) and on the server (typically, 50% system cpu, 45% idle, 5% user) and it is clear that we need more power in the system. The question is: how can we best achieve this? "Best" includes ease of adminstration, floor-space required and maintenance, as well as low cost. Two solutions come to mind. First, we could get a 4/260 with one or more big disks; split the ethernet with a bridge (I believe they act as smart filters and pass only those packets which need to reach the other half, absorbing the others. Confirmation?) and put half the net on that new machine. I want to avoid using a whole new sub-net if possible. Users' filesystems would also be split across the two machines. Secondly, we could get several small (300Mb ?) disks and plug them into currently diskless machines. Each of those would be a server for one or two of the remaining diskless machines. Users' filespace would be increased by that saved from the client partitions now in use. In addition, we may be able to add another disk to the current server to increase users' space. At present, I favour the first but I can see that it may be rather more expensive. The arguments against the second, as I see it, are that backing-up many more machines is a hassle and uses more tapes and time (both of which mean money also); the ethernet loading is not reduced *that* much; and machine-loading. Does any one know whether a 4/110 or 3/160 can happily serve 1 or 2 others *and* run suntools and a "typical" application mix, all without server and clients suffering badly? Does it help if only the same architectures are served? (Clearly, it requires less disk space, but does it take fewer computrons as well?) Thanks if you can help out. If I get direct mail, I'll summarize afterwards. Paul Leyland JANET: pcl@uk.ac.oxford.robots UUCP: <atlantic>!mcvax!ukc!ox-rob!pcl VOICE +44-865-273157
krempel@pacrat.npac.syr.edu (Henry B.J. Krempel) (12/20/88)
What I would do is split the network into 2 subnets. This insures conclusively that the network traffic is divided, without relying on "smartness" of bridges. It also makes solving network problems easier to track down. I would buy another system, like the 4/260 you mentioned, or I might favor a 4/280S with a cartidge drive (it's cheaper) and for backups you might use a 2GB video cartridge, like the one Perfect Byte sells. The new system should have 2 ethernet interfaces, to serve as a gateway for the new subnet you are creating. Then you can do one of the following: Campus Ethernet --------|-----------------------------------------------| | | server1: 3/180S new server | | | | 5 - 3/50's 5 - 3/50s Sun-3 diskless machines Sun 4 diskless OR: Campus Ethernet --------|-------------------------------------------- | server1: 3/180S | | 5 - 3/50's Sun-3 diskless machines new server | | 5 - 3/50s Sun 4 diskless It depends on how much you like heirarchy, also, if you are doing backups for the new server using the 3/180S' tape drive, the second option might be better. Then, you can set it up with either fstab or automounter so that users get their home directories wherever they are, putting peoples directories on networks where they do most of their work. Also, set up mail so all of this appears as one host, with the mail directory being NFS mounted. This has a few advantages: Server1 is a homogenous server, a sun-3 serving sun-3's, easier to maintain, and there have been performance problems seen in earlier issues with Sun 3's serving Sun-4's. The 4MB 50's are spread across two different networks, drastically reducing network load. I run a network with 6-3/50's on it and a bunch of 8MB systems, and the network load is fine. You are backing up 2 systems, instead of one for each workstation. Henry B. J. Krempel <krempel@pacrat.npac.syr.edu> Syracuse University 250 Machinery Hall Syracuse, N.Y. 13244
neil@uunet.uu.net (Neil Gorsuch) (12/20/88)
pcl@robots.oxford.ac.uk (Paul Leyland) writes: >I would welcome advice, thoughts and opinions on the following problem. >How do we upgrade a small-to-medium size system into a medium-to-large >size one? > >The question is: how can we best achieve this? "Best" includes ease of >adminstration, floor-space required and maintenance, as well as low cost. I recently had a conversation with a gentleman at Los Alamos National Laboratory about the relative merits and costs of using 3/50's and 3/xxx's as files servers for diskless clients. He pointed out that a 3/50 for about $3500 and a 300 Mb CDC Wren shoebox drive system for about $2900, total about $6400, will serve 3 to 5 diskless 3/50's or 3/60's without any problems whatsoever, as long as the server 3/50 is only used as a server. In fact, the stock 4 Mbytes of memory is more than adequate for the network server daemons and Sunos. Compare that to maybe 5 to 10 times as much money for an "official" sun 3/xxx server with eagle drives that can handle 15 or so diskless clients comfortably, and the price/performance ratio is clearly in favor of using 3/50's as file servers. If backup is a concern, buy an Exabyte 2 Gbyte 8 mm tape drive from someone for about $4500. This route is more of a pain to setup, but the total cost reductions are quite dramatic. neil@cpd.com uunet!ccicpg!zardoz!neil (714) 547-3000