fdisk(1M)
NAME
fdisk - create or modify fixed disk partition table
SYNOPSIS
fdisk [-o offset] [-s size] [-P fill_patt] [-S geom_file]
[-w | r | d | n | I | B | t | T | g | G | R] [-
F fdisk_file] [ [-v] -W { fdisk_file | -}] [-h] [-
b masterboot] [ -A id : act : bhead : bsect : bcyl : ehead :
esect : ecyl : rsect : numsect] [ -D id : act : bhead: bsect
: bcyl : ehead: esect : ecyl : rsect : numsect] rdevice
DESCRIPTION
This command is used to do the following:
o Create and modify an fdisk partition table on x86 sys-
tems
o Create and modify an fdisk partition table on remov-
able media on SPARC or x86 systems
o Install the master boot record that is put in the
first sector of the fixed disk on x86 systems only
This table is used by the first-stage bootstrap (or
firmware) to identify parts of the disk reserved for dif-
ferent operating systems, and to identify the partition
containing the second-stage bootstrap (the active Solaris
partition). The rdevice argument must be used to specify the
raw device associated with the fixed disk, for example,
/dev/rdsk/c0t0d0p0.
The program can operate in three different modes. The first
is interactive mode. In interactive mode, 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.
In interactive mode, if there is no partition table on the
disk, the user is given the options of creating a default
partitioning or specifying the initial table values. The
default partitioning allocates the entire disk for the
Solaris system and makes the Solaris system partition
active. In either case, when the initial table is created,
fdisk also writes out the first-stage bootstrap (x86 only)
code along with the partition table.
The second mode of operation is used for automated entry
addition, entry deletion, or replacement of the entire
fdisk table. This mode can add or delete an entry described
on the command line. In this mode the entire fdisk table can
be read in from a file replacing the original table. fdisk
can also be used to create this file. There is a command
line option that will cause fdisk to replace any fdisk
table with the default of the whole disk for the Solaris
system.
The third mode of operation is used for disk diagnostics. In
this mode, a section of the disk can be filled with a user
specified pattern, and mode sections of the disk can also be
read or written.
Menu Options
The menu options for interactive mode 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 (SOLARIS, MS-
DOS, UNIX, 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 start-
ing cylinder number where the partition will fit. In
either case, if the partition would overlap an exist-
ing 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.
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.
OPTIONS
The following options apply to fdisk:
-A id:act:bhead:bsect:bcyl:ehead:esect:ecyl:rsect:numsect
Add a partition as described by the argument (see the
-F option below for the format). Use of this option
will zero out the
VTOC on the Solaris partition if the fdisk table
changes.
-b master_boot
Specify the file master_boot as the master boot pro-
gram. The default master boot program is
/usr/lib/fs/ufs/mboot.
-B Default to one Solaris partition that uses the whole
disk.
-d Turn on verbose debug mode. This will cause fdisk to
print its state on stderr as it is used. The output
from this option should not be used with -F.
-D id:act:bhead:bsect:bcyl:ehead:esect:ecyl:rsect:numsect
Delete a partition as described by the argument (see
the -F option below for the format). Note that the
argument must be an exact match or the entry will not
be deleted! Use of this option will zero out the VTOC
on the Solaris partition if the fdisk table changes.
-F fdisk_file
Use fdisk file fdisk_file to initialize table. Use of
this option will zero out the VTOC on the Solaris
partition if the fdisk table changes.
The fdisk_file contains up to four specification
lines. Each line is delimited by a new-line character
(0. If the first character of a line is an asterisk
(*), the line is treated as a comment. Each line is
composed of entries that are position-dependent, are
separated by ``white space'' or colons, and have the
following format:
id act bhead bsect bcyl ehead esect ecyl rsect numsect
where the entries have the following values:
id This is the type of partition and the correct
numeric values may be found in fdisk.h.
act This is the active partition flag; 0 means not
active and 128 means active.
bhead This is the head where the partition starts. If
this is set to 0, fdisk will correctly fill this
in from other information.
bsect This is the sector where the partition starts.
If this is set to 0, fdisk will correctly fill
this in from other information.
bcyl This is the cylinder where the partition starts.
If this is set to 0, fdisk will correctly fill
this in from other information.
ehead This is the head where the partition ends. If
this is set to 0, fdisk will correctly fill this
in from other information.
esect This is the sector where the partition ends. If
this is set to 0, fdisk will correctly fill this
in from other information.
ecyl This is the cylinder where the partition ends.
If this is set to 0, fdisk will correctly fill
this in from other information.
rsect The relative sector from the beginning of the
disk where the partition starts. This must be
specified and can be used by fdisk to fill in
other fields.
numsect
The size in sectors of this disk partition. This
must be specified and can be used by fdisk to
fill in other fields.
-g Get the label geometry for disk and display on stdout
(see the -S option for the format).
-G Get the physical geometry for disk and display on
stdout (see the -S option for the format).
-h Issue verbose message; message will list all options
and supply an explanation for each.
-I Forgo device checks. This is used to generate a file
image of what would go on a disk without using the
device. Note that you must use -S with this option
(see above).
-n Don't update fdisk table unless explicitly specified
by another option. If no other options are used, -n
will only write the master boot record to the disk. In
addition, note that fdisk will not come up in interac-
tive mode if the -n option is specified.
-o offset
Block offset from start of disk. This option is used
for -P, -r, and -w. Zero is assumed when this option
is not used.
-P fill_patt
Fill disk with pattern fill_patt. fill_patt can be
decimal or hex and is used as number for constant long
word pattern. If fill_patt is #, then pattern is
block # for each block. Pattern is put in each block
as long words and fills each block (see -o and -s).
-r Read from disk and write to stdout. See -o and -s,
which specify the starting point and size of the
operation.
-R Treat disk as read-only. This is for testing purposes.
-s size
Number of blocks to perform operation on (see -o).
-S geom_file
Set the label geometry to the content of the
geom_file. The geom_file contains one specification
line. Each line is delimited by a new-line character
(0. If the first character of a line is an asterisk
(*), the line is treated as a comment. Each line is
composed of entries that are position-dependent, are
separated by white space, and have the following for-
mat:
pcyl ncyl acyl bcyl nheads nsectors sectsiz
where the entries have the following values:
pcyl This is the number of physical cylinders for the
drive.
ncyl This is the number of usable cylinders for the
drive.
acyl This is the number of alt cylinders for the
drive.
bcyl This is the number of offset cylinders for the
drive (should be zero).
nheads
The number of heads for this drive.
nsectors
The number of sectors per track.
sectsiz
The size in bytes of a sector.
-t Adjust incorrect slice table entries so that they
will not cross partition table boundaries.
-T Remove incorrect slice table entries that span parti-
tion table boundaries.
-v Output the HBA (virtual) geometry dimensions. This
option must be used in conjunction with the -W flag.
This option will work for platforms which support vir-
tual geometry. (x86 only)
-w Write to disk and read from stdin. See -o and -s,
which specify the starting point and size of the
operation.
-W - Output the disk table to stdout.
-W fdisk_file
Create an fdisk file fdisk_file from disk table. This
can be used with the -F option below.
FILES
/dev/rdsk/c0t0d0p0
Raw device associated with the fixed disk.
/usr/lib/fs/ufs/mboot
Default master boot program.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Architecture | IA and SPARC |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
SEE ALSO
uname(1), fmthard(1M), prtvtoc(1M), attributes(5)
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 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 con-
troller, the disk itself, the driver, or the confi-
guration of the fixed disk.
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