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RANDOM NOTES ON THE QLOGICFAS SCSI DRIVER

This driver supports the Qlogic FASXXX family of chips.  This driver

only works with the ISA, VLB, and PCMCIA versions of the Qlogic

FastSCSI!  cards as well as any other card based on the FASXX chip

(including the Control Concepts SCSI/IDE/SIO/PIO/FDC cards).

This driver does NOT support the PCI version.  Support for these PCI

Qlogic boards:

        * IQ-PCI

        * IQ-PCI-10

        * IQ-PCI-D

is provided by the qlogicisp.c driver.  Check README.qlogicisp for

details.

Nor does it support the PCI-Basic, which is supported by the

'am53c974' driver.

PCMCIA SUPPORT

This currently only works if the card is enabled first from DOS.  This

means you will have to load your socket and card services, and

QL41DOS.SYS and QL40ENBL.SYS.  These are a minimum, but loading the

rest of the modules won't interfere with the operation.  The next

thing to do is load the kernel without resetting the hardware, which

can be a simple ctrl-alt-delete with a boot floppy, or by using

loadlin with the kernel image accessible from DOS.  If you are using

the Linux PCMCIA driver, you will have to adjust it or otherwise stop

it from configuring the card.

I am working with the PCMCIA group to make it more flexible, but that

may take a while.

ALL CARDS

The top of the qlogic.c file has a number of defines that controls

configuration.  As shipped, it provides a balance between speed and

function.  If there are any problems, try setting SLOW_CABLE to 1, and

then try changing USE_IRQ and TURBO_PDMA to zero.  If you are familiar

with SCSI, there are other settings which can tune the bus.

It may be a good idea to enable RESET_AT_START, especially if the

devices may not have been just powered up, or if you are restarting

after a crash, since they may be busy trying to complete the last

command or something.  It comes up faster if this is set to zero, and

if you have reliable hardware and connections it may be more useful to

not reset things.

SOME TROUBLESHOOTING TIPS

Make sure it works properly under DOS.  You should also do an initial FDISK

on a new drive if you want partitions.

Don't enable all the speedups first.  If anything is wrong, they will make

any problem worse.

IMPORTANT

The best way to test if your cables, termination, etc. are good is to

copy a very big file (e.g. a doublespace container file, or a very

large executable or archive).  It should be at least 5 megabytes, but

you can do multiple tests on smaller files.  Then do a COMP to verify

that the file copied properly.  (Turn off all caching when doing these

tests, otherwise you will test your RAM and not the files).  Then do

10 COMPs, comparing the same file on the SCSI hard drive, i.e. "COMP

realbig.doc realbig.doc".  Then do it after the computer gets warm.

I noticed my system which seems to work 100% would fail this test if

the computer was left on for a few hours.  It was worse with longer

cables, and more devices on the SCSI bus.  What seems to happen is

that it gets a false ACK causing an extra byte to be inserted into the

stream (and this is not detected).  This can be caused by bad

termination (the ACK can be reflected), or by noise when the chips

work less well because of the heat, or when cables get too long for

the speed.

Remember, if it doesn't work under DOS, it probably won't work under

Linux.