SCSI system...SCSI boot drives
Is there an advantage to implementing SCSI floppy, SCSI harddrives, and SCSI CDROM? Would we be able to disable the IDE and floppy controllers. Would this free up system resources and increase overall system performance?
A guy on the sysop forum disabled his ISA bus and increased his system performance.
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Subject: Re: Disabling ISA bus...
sysopt.com
>>>>My system is totally pci, nothing is sitting in any of my ISA slots... I have disabled my plug and play bus for ISA and my enumerator, as well as leaving all my irq's to pci/pnp. I have noticed about a 7% speed increase in doing so... What else do I have to do to knock out my ISA bus from sucking my system into that vile 8mhz hell...
a response
Increase the PCI latency setting. I heard it would increase the performance up to 20%. I tried it via a 3rd party software program called "tweak bios" but it didn't do me any good but i figure it was since it was a software program and not the bios is the reason it did nothing for me. I found that tip out of "boot" magazine so i figure it must be correct. (BTW you can get a free issue and CD from them bootnet.com I highly recommend it.)<<<<
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Six of the dozen or so computers I use at work are SCSI based. I did not set them up originally. I do not know the issues on original set-up. They are user friendly when it comes to swapping components. I have taken harddrives and CD ROM drives from "parts machines" and installed them in the "working" machines with very little trouble.
Mixing IDE and SCSI in a boot sequence seems to pose some problems. Three machines were delivered with the IDE LS120 drive substituted for the floppy drive. The guy that did it for me told me he had trouble setting the LS120 as a boot drive. (he did and it works)
SCSI LS120 is now available and would most likely be a better option if we were to try and make a SCSI based system.
I found the following on a news group. I do not know how to post a link to the site. The author(s) talk of Adaptec 78xx SCSI controllers that support boot drives for any SCSI ID. It would be my understanding that CDROM, LS120, and harddrive could all be set as boot drives. Also comments about mixing IDE and SCSI boot devices
Regards
Zeuspaul
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Subject: Re: Two SCSI devices in one system?
Yes the 78xx chipset is one of Adaptec's best, it's
on the 2940UW's and some 2940U's that were
built specially for Server useage. And you alter
the termination thru the on-controller bios for
it's term, most peripherals still use the"jumper"
method. SCAM is nice, though I prefer to manually
set the ID's so I can assign the order.
>>>Tom L. wrote:
Not trying to start an argument, however -
I have an Adaptec 3940UW running a fully SCAM (Scsi Configured
automatically) compliant set of devices (CD,CD-R, CD-RW and hard
drives). The host adapter automatically assigns SCSI ID and termination for all devices. More and more SCSI devices are being made that are SCAM compliant and making all SCSI users life easier. Also, using the Adaptec AIC78XX chip (i.e. AHA-29/3940) allows the user to boot from any bootable device an any channel regardless of SCSI ID, a very nice feature for users of multiple OS's.> --
Later,
Tom L.<<<<
>>> But you still have to set the jumper to diable the terminating
> resistor, is it right? That's true for all the device in my system though. Maybe something new will have Plug-n-Play features for termination also!
Yes, you have to set the termination jumper on the devices at the ends of the chain. The only auto-termination devices I've ever seen are the controllers. Drives have no way of knowing that they are at the end of the chain. The ID number also must be set manually on everything but the controller. The controller is set to 7 as the default, but can be changed via a utility. The boot device is usually 0 and the devices are counted upwards (that is drive 80 - C: is 0, 81 is the next highest device found). Some systems work the other way
(mainly IBM PS/2) and count down from 6. SCSI wide allows devices to be numbered 8 through 15 as well.
If one has both IDE and SCSI devices it gets more complicated. Recent BIOS will allow either IDE or SCSI to be the boot device (drive 80). This is really up to the particular BIOS however.
Keith R. Williams<<<<
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