Return to BSD News archive
Xref: sserve comp.unix.bsd:3825 comp.sys.ibm.pc.hardware:29345 Newsgroups: comp.unix.bsd,comp.sys.ibm.pc.hardware Path: sserve!manuel!munnari.oz.au!mips!decwrl!csus.edu!netcom.com!alm From: alm@netcom.com (Andrew Moore) Subject: Disklabeling (was Re: Another Adaptec Question) Message-ID: <#79m_a.alm@netcom.com> Date: Mon, 17 Aug 92 22:29:21 GMT Organization: Netcom - Online Communication Services (408 241-9760 guest) References: <1992Aug16.144341.24052@Informatik.TU-Muenchen.DE> <15776@star.cs.vu.nl> <1992Aug17.173807.2309@Informatik.TU-Muenchen.DE> Distribution: world,fj,spec Lines: 46 In article <1992Aug17.173807.2309@Informatik.TU-Muenchen.DE> rommel@Informatik.TU-Muenchen.DE (Kai-Uwe Rommel) writes: >In article <15776@star.cs.vu.nl> kjb@cs.vu.nl (Kees J. Bot) writes: >>rommel@Informatik.TU-Muenchen.DE (Kai-Uwe Rommel) writes: >>> >>>In article <7@tama.spec.co.jp> amurai@tama.spec.co.jp (Atsushi Murai) writes: >>>>ariticle is not ..but) and Fujitsu M2266SA 1.2 GB Disks. Functionality >>>>is good but it looks like loosing a space about 200MB (above 1Gbyte). >>>>And some guy let me know about this is a known problem of 1542B and >>>>Adaptec will be fixed by new board - 1542C. (Oh well.....) >>>>[...] >>It has nothing to do with heads, sectors or cylinders. The group 0 SCSI >>read/write commands allow only for a 21 bit block address limiting one >>to 2 megablocks, which is 1GB at the usual 512 bytes per block. > >We don't talk about smart OSes like 386BSD :-) but the original poster >asked why he doesn't see all the space under DOS/Novell. There it has to >do quite a lot with heads/tracks/sectors ... > >>The group 1 SCSI read/write commands offer a 32 bit block address >>however, but not all O.S.'s are smart enough to use those commands. >> >>>Adaptec has now a new mapping scheme with 256 heads and 64 sectors per >>>track, [etc...] >> >>At least the 64 sectors per track number is wrong, you can't have more >>than 63 sectors on a track. I don't like the 256 heads per track >>either, I know of one (1.5GB) disk with an AT interface that uses the >>top 2 head bits for two more cylinder bits. This limits the number of >>heads per track to 64, but allows for 4096 cylinders. I don't know if >>this is a normal way of addressing bigger disks under DOS. Anyone? > >Sorry, for those off-by-one errors, here is the original text from the >Adaptec README file: > >--quote-- >To eliminate the 1 Gigabyte limit, Adaptec's new extended >translation feature uses 255 heads and 63 sectors, >extending the disk drive capacity limit under >DOS to 8 Gigabytes. >--end-quote-- To return to 386BSD and disklabeling a SCSI drive: am I correct in assuming that the specification of # of cylinders, sectors per cylinder, etc does not matter at all, so long as the total number of blocks is correct?