Return to BSD News archive
#! rnews 2576 bsd Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!simtel!daffy!uwvax!uwm.edu!hookup!solaris.cc.vt.edu!news.mathworks.com!newsfeed.internetmci.com!news.msfc.nasa.gov!pendragon.jsc.nasa.gov!ames!lll-winken.llnl.gov!parc!dunvegan!macleod From: macleod@adoc.xerox.com (Peter MacLeod) Newsgroups: comp.periphs.scsi,comp.os.linux.hardware,comp.unix.bsd.freebsd.misc,comp.os.linux.setup Subject: Re: SCSI PCI host adapter Followup-To: comp.periphs.scsi,comp.os.linux.hardware,comp.unix.bsd.freebsd.misc,comp.os.linux.setup Date: 7 Sep 1995 00:57:55 GMT Organization: Xerox Desktop Document Systems, Palo Alto, CA Lines: 32 Message-ID: <42lg2j$pks@news.parc.xerox.com> 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> NNTP-Posting-Host: dunvegan.adoc.xerox.com X-Newsreader: TIN [version 1.2 PL2] Xref: euryale.cc.adfa.oz.au comp.periphs.scsi:37136 comp.os.linux.hardware:15381 comp.unix.bsd.freebsd.misc:5774 comp.os.linux.setup:19851 Sam Daniel (daniel@netcom.com) wrote: : 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. The whole idea behind SCSI was that the protocol over the wire was standardized, and that therefore the controller shouldn't matter. It should be the drive that decides where the bits go on the platters. Unfortunately, the problem on the PC machines is that it is up to the BIOS code on the card to decide how the (track, sector) addresses in the BIOS calls get mapped into SCSI block addresses. In the case of real operating systems which have SCSI managers and drivers, and ignore the whole BIOS mess, I would think that disks swapped between cards would be compatible, especially if one didn't try to boot off of the SCSI drive. This might be naive, however--many card vendors don't understand the purpose of a standard like SCSI, and might "be clever" and break it for no good reason. --P