*BSD News Article 50249


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Newsgroups: comp.periphs.scsi,comp.os.linux.hardware,comp.unix.bsd.freebsd.misc,comp.os.linux.setup
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From: cracauer@wavehh.hanse.de (Martin Cracauer)
Subject: Re: SCSI PCI host adapter
Message-ID: <1995Sep5.120319.21932@wavehh.hanse.de>
Organization: The Internet
References: <418r3m$9c6@trauma.rn.com> <1995Aug30.074902.1035@wavehh.hanse.de> <42846g$2e9@trauma.rn.com> <42crke$hg@reason.cdrom.com> <42ea9k$1sd@trauma.rn.com> <danielDEE700.Guv@netcom.com>
Date: Tue, 5 Sep 95 12:03:19 GMT
Lines: 50
Xref: euryale.cc.adfa.oz.au comp.periphs.scsi:36666 comp.os.linux.hardware:14784 comp.unix.bsd.freebsd.misc:5454 comp.os.linux.setup:18995

daniel@netcom.com (Sam Daniel) writes:

>larry@rn.com (Larry Snyder) writes:

>>I'm stating for example, if I installed FreeBSD using the 2940
>>controller, I should be able to remove the 2940 and install the
>>NCR controller and be able to boot the machine and access the data
>>on the hard driving using the NCR.

>>Is this not correct?  In any case, the data written (FreeBSD)
>>with the 2940 not accessable using the NCR card (after removing
>>the 2940 and inserting the NCR card in the PCI buss)

>Sorry, but this is often the case. I've had to reformat drives after
>switching controller cards. Each manufacturer can write the bits any
>way they please on the disk.

>In any case, when I went shopping for an NCR to try out, I was told
>that NCR and Adaptec were not compatible.

I posted this a few days ago, but maybe it didn't get through...

You can have a machine that boots from a NCR, shut it down, change the
controller of the boot drive to an 2940 and boot. No boot problems,
nothing to switch, no performance penality.

Of course, you have to have both drivers in the kernel. They are not
driver compatible, as your shop told you. But FreeBSD detencts which
one is in the machine and uses the right driver for it.

To make this happen, you have to have a disk geometry that is both
valid on the AHA and the NCR. Valid means: The BIOS boot loader must
be able to find the partitions. If you use just the FreeBSD-Install on
an empty disk, that will not work.

I usually label my drives under MS-DOS (fdisk.exe) for the first
time. Then boot with the FreeBSD install-bootdisk. It uses the
existing label which includes the disk geometry chosen by MS-DOS and
doesnt't touch the geometry even when changing all partitions. At
least on my machine (Asus-Triton-Board), the geometry chosen by MS-DOS
was a geometry that made the BIOS able to find the partitions at boot
time, both with the NCR and the AHA controller.

Hope this helps.

Martin
-- 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Martin Cracauer <cracauer@wavehh.hanse.de>. No NeXTMail, please.
 Norderstedt/Hamburg, Germany. Fax +49 40 522 85 36. This is a 
 private address. At (netless) work programming in data analysis.