fdisk(1M) UNIX System V(Base System) fdisk(1M)
NAME
fdisk - create or modify hard disk partition table
SYNOPSIS
fdisk [argument]
DESCRIPTION
This command is used to create and modify the partition table that is put
in the first sector of the hard disk. This table is used by DOS and by
the first-stage bootstrap to identify parts of the disk reserved for
different operating systems, and to identify the partition containing the
second-stage bootstrap (the active partition). The optional argument can
be used to specify the raw device associated with the hard disk; the
default value is /dev/rdsk/0s0 for integral disks. For SCSI disks, there
is no default value. However if the default on your system is set to
0s0, then it is linked to /dev/rdsk/c0t0d0s0. If the default is set to
1s0, then it is linked to /dev/rdsk/c0t1d0s0.
The program displays the partition table as it exists on the disk, and
then presents a menu allowing the user to modify the table. The menu,
questions, warnings, and error messages are intended to be self-
explanatory.
If there is no partition table on the disk, the user is given the option
of creating a default partitioning or specifying the initial table
values. The default partitioning allows 10% of the disk for MS-DOS and
90% for the UNIX System, and makes the UNIX System partition active. In
either case, when the initial table is created, fdisk also writes out the
first-stage bootstrap code [see hd(7)] along with the partition table.
After the initial table is created, only the table is changed; the
bootstrap is not modified.
Menu Options
The following are the menu options given by the fdisk program:
Create a partition
This option allows the user to create a new partition. The maximum
number of partitions is 4. The program will ask for the type of the
partition (MS-DOS, UNIX System, or other). It will then ask for the
size of the partition as a percentage of the disk. The user may
also enter the letter c at this point, in which case the program
will ask for the starting cylinder number and size of the partition
in cylinders. If a c is not entered, the program will determine the
starting cylinder number where the partition will fit. In either
case, if the partition would overlap an existing partition, or will
not fit, a message is displayed and the program returns to the
original menu.
Change Active (Boot from) partition
This option allows the user to specify the partition where the
first-stage bootstrap will look for the second-stage bootstrap,
otherwise known as the active partition.
10/89 Page 1
fdisk(1M) UNIX System V(Base System) fdisk(1M)
Delete a partition
This option allows the user to delete a previously created
partition. Note that this will destroy all data in that partition.
Exit This option writes the new version of the table created during this
session with fdisk out to the hard disk, and exits the program.
Cancel
This option exits without modifying the partition table.
DIAGNOSTICS
Most messages will be self-explanatory. The following may appear
immediately after starting the program:
fdisk: cannot open <device>
This indicates that the device name argument is not valid.
fdisk: unable to get device parameters for device <device>
This indicates a problem with the configuration of the hard disk,
or an error in the hard disk driver.
fdisk: error reading partition table
This indicates that some error occurred when trying initially to
read the hard disk. This could be a problem with the hard disk
controller or driver, or with the configuration of the hard disk.
This message may appear after selecting the Exit option from the menu.
fdisk: error writing boot record
This indicates that some error occurred when trying to write the
new partition table out to the hard disk. This could be a problem
with the hard disk controller, the disk itself, the driver, or the
configuration of the hard disk.
FILES
/dev/rdsk/0s0 for integral disks
/dev/rdsk/c?t?d?s0 for SCSI disks
SEE ALSO
mkpart(1M), disk(7), hd(7).
NOTES
Compatible with MS-DOS Versions 3.2, 3.3, and 4.0. Partitions set up
using the MS-DOS 4.0 fdisk command that are greater than 32 MB will
appear in the UNIX System display as "other". Partitions created with
MS-DOS that are less than 32 MB will appear correctly as DOS partitions.
The DOS 4.01 fdisk program assumes it can store diagnostic information in
cylinder 1020 on the hard disk. If a UNIX System partition is created
that uses cylinder 1020, DOS 4.01 fdisk will be unable to create a DOS
partition. Therefore, the user must either create the UNIX System
partition at the front of the disk so that cylinder 1020 is not used, or
Page 2 10/89
fdisk(1M) UNIX System V(Base System) fdisk(1M)
create the DOS partition using the UNIX System fdisk (not DOS fdisk) and
never delete it.
When setting up a DOS 4.01 partition on the hard disk to co-reside with a
UNIX partition that has already been set up, DO NOT allow fdisk to create
the largest possible partition and make it active (as the fdisk prompt
requests). Instead, the user should manually set it up to line up
against the UNIX partition. Note that this applies to when the user
boots DOS 4.01 from floppy disk (not from within UNIX) and runs fdisk.
10/89 Page 3