tim@cit-vax.Caltech.Edu (Timothy L. Kay) (10/16/89)
I recently posted that we were having trouble when we tried to hang too many devices (6) off the 80GTB SCSI bus. I got many very useful responses, and lots of good information. It turns out that I made a bad assumption. I had assumed that Silicon Graphics would ship their $100,000 machine configured correctly! It turns out that they sent it out with too many terminators already on the bus!!! When I added our drives, I very carefully removed the terminators that were supposed to be there (on the disk drive), but I failed to remove the terminators on the SGI supplied tape drive. Thing is that they should never have been there in the first place!!! Grrrrr. Tim
jmb@patton.sgi.com (Jim Barton) (10/16/89)
In article <12249@cit-vax.Caltech.Edu>, tim@cit-vax.Caltech.Edu (Timothy L. Kay) writes: > > I recently posted that we were having trouble when we tried to > hang too many devices (6) off the 80GTB SCSI bus. I got many > very useful responses, and lots of good information. > > It turns out that I made a bad assumption. I had assumed that Silicon > Graphics would ship their $100,000 machine configured correctly! It > turns out that they sent it out with too many terminators already on > the bus!!! When I added our drives, I very carefully removed the > terminators that were supposed to be there (on the disk drive), but I > failed to remove the terminators on the SGI supplied tape drive. Thing > is that they should never have been there in the first place!!! > > Grrrrr. > > Tim Grrrrr yourself. The 80GTB was configured correctly. The bus has to be terminated somewhere. To ease manfucturing, we always set up the tape drive as the last device on the bus and terminate it, that way the folks who bolt the machines together can do it with fewer errors. When you add device on the bus AFTER the tape drive, you are doing something even our FE's are trained not to do: they also will move the tape drive to last on the bus for simplicity. If you have NO terminators on your bus now, you are also violating the SCSI specification; I hope the data goes out to your disk realiably! Don't bash us when you do it yourself. Your take your own risks. -- Jim Barton Silicon Graphics Computer Systems "UNIX: Live Free Or Die!" jmb@sgi.sgi.com, sgi!jmb@decwrl.dec.com, ...{decwrl,sun}!sgi!jmb "I used to be disgusted, now I'm just amused." - Elvis Costello, 'Red Shoes' --
kaufman@Neon.Stanford.EDU (Marc T. Kaufman) (10/17/89)
In article <43065@sgi.sgi.com> jmb@patton.sgi.com (Jim Barton) writes: >When you add device on the bus AFTER the tape drive, you are doing something >even our FE's are trained not to do... Incredible. Remind me never to have one of your "trained" FEs work on any equipment I am responsible for. Marc Kaufman (kaufman@Neon.stanford.edu)
markb@denali.sgi.com (Mark Bradley) (10/17/89)
In article <12492@polya.Stanford.EDU>, kaufman@Neon.Stanford.EDU (Marc T. Kaufman) writes: > In article <43065@sgi.sgi.com> jmb@patton.sgi.com (Jim Barton) writes: > > >When you add device on the bus AFTER the tape drive, you are doing something > >even our FE's are trained not to do... > > Incredible. Remind me never to have one of your "trained" FEs work on any > equipment I am responsible for. > > Marc Kaufman (kaufman@Neon.stanford.edu) I think you missed the point. Our FE's are trained NOT to have multiple terminators where they are NOT supposed to be. That is, if OUR FE's install one of OUR devices onto an already configured SCSI device system, they are to make certain that the bus is correctly terminated (that is, terminator only on the *terminal* device). markb -- Mark Bradley "Faster, faster, until the thrill of I/O Subsystems speed overcomes the fear of death." Silicon Graphics Computer Systems Mountain View, CA 94039-7311 ---Hunter S. Thompson Disclaimer: Anything I say is my opinion. If someone else wants to use it, it will cost...
tim@cit-vax.Caltech.Edu (Timothy L. Kay) (10/19/89)
Let me put an end to the not-so-constructive discussion about Silicon Graphics that has resulted from a simple informative posting I made last week. I posted the _fact_ that SGI shipped our 80GTB with the SCSI bus over-terminated. Jim Barton and others from SGI misinterpretted what I said in the posting and said that I was configuring the bus incorrectly. He was refering to my having placed devices on the SCSI bus after the tape drive. He claimed that the tape drive was supposed to be the last device on the bus. It wasn't that way when they shipped it, and he missed an even more important point. The disk drive was the last device on the bus, and *both* the disk drive and the tape drive had their terminators in place. The manufacturing people (not the FE's) were responsible, and they did something they shouldn't have. I talked to Jim Barton on the phone and explained again what I had said in the article. He agreed that the machine was shipped misconfigured. He said that he would make sure that it doesn't happen again. Thank you, Mr. Barton! Since I fixed the problem, our SCSI bus has worked rock solid with five devices on it. We plan to add another one or possibly two devices (five 300 MB disks and two tape drives). Now, let me comment on the equipment. We use the machine as part of our work in the Caltech Computer Graphics Lab. It is a fabulous machine. It out performs its competitors' top-of-the-line machines, and it isn't even the fastest machine you can get from SGI (by a long shot). If you ask me by email, I'll tell you whose equipment I am refering to. In conclusion, I think SGI makes *great* equipment. They were slightly slow at taking constructive criticism, but I firmly believe that Jim Barton will see (has seen?) to it that the problem is fixed. If it weren't for this newsgroup, I would have only the salesperson to tell the problem, and that would probably have gone nowhere. So, this forum served a good purpose. Tim Kay Caltech 818-449-6017 P.S. I hope the damage from the earthquake is repaired soon enough for the people at SGI to see my comments.
jmb@patton.sgi.com (Jim Barton) (10/20/89)
In article <12289@cit-vax.Caltech.Edu>, tim@cit-vax.Caltech.Edu (Timothy L. Kay) writes: ... resolution of the SCSI bus problem ... > > Tim Kay > Caltech > 818-449-6017 > > P.S. I hope the damage from the earthquake is repaired soon enough > for the people at SGI to see my comments. In case you're curious, all the SGI machines at home base here survived fine, and we were back up on the air, networks and all, by 11:00 Wednesday morning. Only a small amount of damage to the factory, and we're back shipping machines. Unfortunately, some of the people who work here had homes in the more damaged areas, and are still having a hard time. -- Jim Barton Silicon Graphics Computer Systems "UNIX: Live Free Or Die!" jmb@sgi.sgi.com, sgi!jmb@decwrl.dec.com, ...{decwrl,sun}!sgi!jmb