Date: Thu, 11 Feb 1999 16:11:30 +0000 From: Mark Ovens <marko@uk.radan.com> To: zhihuizhang <bf20761@binghamton.edu> Cc: Bill Hamilton <billh@finsco.com>, freebsd-questions@FreeBSD.ORG Subject: Re: Partition with Partition Magic Message-ID: <36C30132.9FAB6430@uk.radan.com> References: <Pine.SOL.L3.93.990211095250.3312A-100000@bingsun2>
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zhihuizhang wrote:
>
> > >
> > > I am using Partition Magic 3.02 and I have free space as a primary
> > > partition. The PC already has Linux, DOS 6, and Windows NT installed.
> > > The pqmagict.exe shows there are three primary partitions available and
> > > their sizes are 31.3MB, 4769.2MB, and 1349.2MB respectively. The first
> > > two are also shown in the DOS fdisk command. The second primary partition
> > > contains 7 subpartition: 4 labeled as Linux Ext2, 2 labeled as Linux swap,
> > > and 1 labeled as NTFS (I guess this is for Windows NT).
> > >
> > > I insert CD-ROM and reboot from it. At the FDISK screen, I see four
> > > entries:
> > >
> > > offset size end name ptype desc subtype
> > > 0 63 62 - 6 unused
> > > 63 64197 64259 wd0s1 2 fat 4 <-- DOS
> > > 64260 9767520 9831779 wd0s2 4 extended 5 <-- extended primary
> > > 9831780 2363180 12594959 wd0s3 3 freebsd 165 CA
> > >
> > > My question is: How come FreeBSD regard the first entry as unused? Why
> > > Partition Magic does not show this entry (It only shows the last three,
> > > wd0s1-wd0s3)? Why there are FOUR entries instead of THREE entries (each
> > > represent a primary partition)? Where does the extra entry (first one)
> > > come from?
> > >
> > > By the way, I installed FreeBSD on another PC successfully and devoted ALL
> > > disk space to FreeBSD on that machine. Still, I got the mysterious first
> > > entry labeled as unused. I read in an installation tutorial that it is
> > > for boot sectors. But for this PC, where can we find those 62 sectors
> > > that seems to be required by FreeBSD?
> > >
> > > Maybe I have to install FreeBSD FIRST (before other OSs) to make sure
> > > FreeBSD can use the first 62 sectors. I try to find the start sector of
> > > the DOS partition to see if there is any conflict, but Partition Magic has
> > > no such information for the first active DOS partition (I can get similar
> > > information on other partitions).
> > >
> > > Anyway, I install FreeBSD on the last partition "successfully" and reboot.
> > >
> > > The System Commander does find the FreeBSD partition. But when I try to
> > > boot from it. It says "read error" and the system halts.
> > >
> > Sounds like bad boot blocks.
> > If you boot off of floppy, perhaps you can repair it.
> > What version of FreeBSD is this?
> >
> I am using FreeBSD 2.2.8. I bought 4 CDs from Walnut Creek. Having read
> some of the followups, I am still confused with the unexplained first
> partition which is 62 sectors (its Ptype is 6 and labeled as "unused").
> Even if I declare ALL disk space to FreeBSD on a machine, that partition
> still occurs.
>
> I hope someone can clarify this for us all. What on earth is its purpose?
As I said in an earlier post, it is the Master Boot Record & Partition
Table area of the disk.
FreeBSD (and other *nixes) show much more detail (i.e. at a lower
level) than DOS/Win apps (e.g. PM).
The Master Boot Record and Partiton Table has to live somewhere on the
disk and it is in the first few (63) sectors.
PM and DOS fdisk don't bother showing this system area (since the user
can't do anything with it, except trash it), FreeBSD, OTOH, shows it,
perhaps confusingly, as an unused "partition".
Ignore it, mine's the same. You'll never get rid of it.
HTH
>
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--
FreeBSD - The Power To Serve http://www.freebsd.org
My Webpage http://www.users.globalnet.co.uk/~markov
_______________________________________________________________
Mark Ovens, CNC Apps Engineer, Radan Computational Ltd. Bath UK
CAD/CAM solutions for Sheetmetal Working Industry
mailto:marko@uk.radan.com http://www.radan.com
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