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Subject: Two Beginer Questions
Date: Sun, 5 Jan 92 03:37:42 -0500
From: Rob Soukoreff <>

Hello Activists:

I seem to be having a problem figuring-out Disk Partitions.  I have
an IDE drive, with MSDOS 5.0, and two questions.

Question #1:
When I use DOS's FDISK, I can only make a maximum of two partitions,
the Primary Partition, and the Extended partition.  Now, since DOS
wants the Primary Partition for itself, this only leaves the extended
partition, which Linux won't accept.  How do you create a partition
of a kind other than Primary or Extended for Linux?

Question #2:
I see in many places people talking about having four partitions on
one hard drive, but I seem only able to create one Primary, and one
Extended partition.  How are these people creating more than two
partitions?  Are they refering to separate Logical DOS Drives within
one Extended Partition?  In particular I am refering to the file:
INSTALL-0.11, by Linus, under the section titled: "Using it."

  Rob Soukoreff

Subject: Re: Two Beginer Questions
Date: Sun, 5 Jan 92 11:47:25 -0500
From: tytso@ATHENA.MIT.EDU (Theodore Ts'o)
To: Rob Soukoreff <>
In-Reply-To: Rob Soukoreff's message of Sun, 5 Jan 92 03:37:42 -0500,

The problem is that the fdisk which MS-DOS uses very limited; it only
knows how to deal with MS-DOS partitions (my 8-bit CP/M machines from
ten years ago did better than that!).

The MS-DOS partitioning scheme does indeed allow for having four
partitions on one hard drive.  The problem was that four is just way too
small of a number.  So what MS-DOS did was that MS-DOS knows how to make
two partitions --- the "Primary" DOS parition, and the "Extended
partition", which is in reality one of the four "Primary" partitions
which can be allocated on a hard disk.  This leaves two other partitions
which MS-DOS FDISK doesn't deal with at all.  Other operating systems,
like OS/2 or Linux, can use them, if they can figure out a way to set up
the other two partitions.  I thought you could indeed use the Extended
partition for Linux, but this is sort of a bad idea, since the wrong
MS-DOS commands could easily trash your Linux filesystem.

If you want to set up one the third and fourth "Primary" partitions,
there are two ways to do this.  The first is to use something like
Norton Utilities, and mess with partition tables with a disk editor.
Norton Utilities' disk editor is actually fairly sophisticated, so it
knows the format of the tables.  You still have to do a bit of manual
calculations to get the ector numbering and double-checking, though.

The other method is to use a more sophisticated FDISK command; the one
supplied with OS/2 will work.  I don't know if there are any other PD
versions of FDISK out there that will do the trick.  There is a fdisk
command under Linux, but currently it will only print out the partition
table.  Eventually you should be able to use the fdisk that comes with
Linux; however, for right now, that's why I only recommend Linux to
people who are willing to hack on it.  :-)

							- Ted

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