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Xref: sserve comp.sys.ibm.pc.hardware.storage:13771 comp.periphs.scsi:26677 comp.sys.next.hardware:13706 comp.os.linux.misc:29881 comp.os.linux.help:65784 comp.os.386bsd.misc:4108 comp.os.386bsd.questions:14500 Newsgroups: comp.sys.ibm.pc.hardware.storage,comp.periphs.scsi,comp.sys.next.hardware,comp.os.linux.misc,comp.os.linux.help,comp.os.386bsd.misc,comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!howland.reston.ans.net!xlink.net!xlink100!subnet.sub.net!flatlin!snert!nextone!nitezki From: Nitezki@NiDat.sub.org (Peter Nitezki) Subject: Re: SCSI on DOS (was Re: More SyQuest infos) Message-ID: <1994Nov16.113401.502@nidat.sub.org> Sender: nitezki@nidat.sub.org Organization: private site of Peter Nitezki, Kraichtal, Germany References: <CzAFDt.48r@prz.tu-berlin.de> Date: Wed, 16 Nov 1994 11:34:01 GMT Lines: 45 In article <CzAFDt.48r@prz.tu-berlin.de> wolf@prz.tu-berlin.de (Thomas Wolfram) writes: ...munch... > BTW, creating a partition table on the SyQuest media with NeXTSTEP's > fdisk gives another result then doing it under DOS because NeXTSTEP > detects 4 heads/17 sectors from the SyQuest drive instead of 64 > heads/32 sectors (with a Adaptec). It might be that this (4/17 > under NEXTSTEP) could be overridden by making an entry in /etc/disktab. > > Also you should use 'fdisk -useAllSectors /dev/rsd?h' because > otherwise fdisk limits the access to those sectors "which are > bios-accessible". To my knowledge these BIOS limits are 1024 > cylinders, 256 heads and 64 sectors, but NEXTSTEP's fdisk limits > then partitions to a size of ~20MB - very strange. > > As for DOS: I was told by a SyQuest person that as long as you use > the SQDRIVER.SYS the translation scheme doesn't matter because the > driver handles it (there is a additional translation done by it). Just to give more background info (and not letting pass a chance to rant on braindead DOS ;-) SCSI disks use a linear address scheme that masks the disk geometry. Therefore, you never get any problems with exchanging SCSI disks between different machines and controllers. Linear addresses are linear under all circumstance. Domestos (aka MessyDOS) fdisk is supposing to work on geometry aware disks. It addresses cylinders, heads, and sectors like in the old days of ST506 and ESDI (and IDE, of course). SCSI controllers have to destroy the linear addressing feature of SCSI in order to support DOS (fdisk) partitioning, thus the need for address translation, and/or need a special fdisk program. Therefore, any SCSI disk that got fdisk partitioned lost its universal exchangability in the process (By the way, since the address translation makes arbitrary choices the optimization features of fdisk and format are very likely to turn out as a shot in your foot). Since NS/FIP knows how to work on fdisk partitioned disks (sigh!) there is a danger to have unexchangable NS disks, a heavy liability in case of Syquest or any similar drives. -- Peter Nitezki | Nitezki@NiDat.sub.org # Blessed art thou who knoweth Staarenbergstr. 44 | Tel.: +49 7251 62495 # not about the pleasure and D-76703 Kraichtal | Fax : +49 7251 69215 # delight of being hooked GERMANY | pgp & NeXTmail ok! # up to the Net. Peter 1,3-5