NAME

fdisk − create or modify fixed 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 fixed disk.  This table is used by MS-DOS (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 fixed disk; the default value is /dev/rdsk/0s0. 

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 allocates 10 percent of the disk for DOS and 90 percent 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 disk(7)) along with the partition table. After the initial table is created, only the table is changed; the bootstrap is not modified.

Upon start-up, the fdisk command will check any extended DOS partition entries, and if they need correcting before they can be used by the UNIX System, you will be prompted:

Do you want to fix the Extended DOS Partitions for UNIX access?
Please type "y" or "n":

Type y to correct the information for the extended DOS partitions.  Type n if you do not want to correct the information. 

WARNING: If you do not correct the information but you still try to mount an extended DOS partition, the system will mount the primary DOS partition as the extended DOS partition, thereby causing great damage to your system.  To make this change take effect, you must reboot the system. 

The DOS partition types are currently listed as DOS12 and DOS16 for the type of file allocation table (FAT) used on each DOS partition. 

Menu Options

The menu options given by the fdisk program are:

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. 

Delete a partition
This option allows the user to delete a previously created partition.  Note that this will destroy all data in that partition.

Display partition table
This option allows the user to display the primary partition list. If there are any extended logical DOS partitions, the system will prompt:

Do you want to display the Extended DOS Partitions?
Please type "y" or "n":

Type y to display the extended DOS partition.  Type n to return to the main menu.  If you type y, the system will then prompt:

Hit return to continue

The system will display a partition number.  This partition number is the name that the DOS partition must be mounted with, i.e., /dev/dsk/0p5 to mount the first extended DOS partition.  Use the following options to include your modifications to the partition table at this time or to cancel the session without modifying the table:

Exit This option writes the new version of the table created during this session with fdisk out to the fixed 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 fixed disk, or an error in the fixed disk driver.

Fdisk: error reading partition table
This indicates that some error occurred when trying initially to read the fixed disk.  This could be a problem with the fixed disk controller or driver, or with the configuration of the fixed disk.

Fdisk: error fixing disk
This indicates that an error occurred when trying to correct the extended DOS partition information. 

Fdisk: error reading extended DOS partition table
This indicates that some error occurred when trying initially to read the fixed disk.  This could be a problem with the fixed disk controller or driver, or with the configuration of the fixed disk.

These messages 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 fixed disk.  This could be a problem with the fixed disk controller, the disk itself, the driver, or the configuration of the fixed disk.

Fdisk: error writing extended DOS partition table
This indicates that some error occurred when trying initially to write to the fixed disk.  This could be a problem with the fixed disk controller or driver, or with the configuration of the fixed disk.

FILES

/dev/rdsk/0s0

SEE ALSO

mkpart(1M), disk(7). 

WARNING

Compatible with MS-DOS Versions 5.0 or earlier. 

ADDED VALUE

This entry, supplied by SunSoft, Inc., contains enhancements to UNIX System V. 

\*U  —  Version 1.0