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Xref: sserve comp.sys.ibm.pc.hardware.storage:13953 comp.periphs.scsi:26788 comp.sys.next.hardware:13748 comp.os.linux.misc:30144 comp.os.linux.help:66493 comp.os.386bsd.misc:4154 comp.os.386bsd.questions:14583 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!uwm.edu!cs.utexas.edu!swrinde!pipex!uunet!zib-berlin.de!cs.tu-berlin.de!elwood!wolf From: wolf@prz.tu-berlin.de (Thomas Wolfram) Subject: Re: SCSI on DOS (was Re: More SyQuest infos) Sender: news@prz.tu-berlin.de (Newsadmin Elwood-PRZ) Message-ID: <CzKz23.7rz@prz.tu-berlin.de> Date: Sun, 20 Nov 1994 19:20:25 GMT Lines: 53 References: <CzAFDt.48r@prz.tu-berlin.de> <1994Nov16.113401.502@nidat.sub.org> Organization: PRZ TU-Berlin X-Newsreader: TIN [version 1.2 PL2] Followup-To: 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 Hi, Peter Nitezki (Nitezki@NiDat.sub.org) wrote: [...] > 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. Unfortunatly true, but fdisk partition tables contain not only the partition locations in cylinder/head/sector specs but as well as in absolute sector specs (starting sector and size)! So smart system/driver devlopers could choose these entries to locate the respective partitions on the removable media. Should be no problem (i.e. naturally) on non-DOS systems to just ignore the pseudo-physical specs in the fdisk partition table. Even the DOS file system doesn't use the c/h/s (except of some not-used entries in the DOS-boot sector) but clusters (linear addressed!), as far as I know. To my mind that should be possible also for fixed disks. Or why not? Thomas -- Thomas Wolfram <thomas@aeon.in-berlin.de> Germany: 0 30 31421171 PRZ TU Berlin <wolf@prz.tu-berlin.de> abroad: +49 30 31421171 EANTC WWW: http://www.prz.tu-berlin.de:/~wolf _____________________________________________________________________________ _____S__I__C____T__R__A__N__S__I__T____G__L__O__R__I__A____M__U__N__D__I_____