System Administration Commands fdisk(1M)
NAME
fdisk - create or modify fixed disk partition table
SYNOPSIS
fdisk [-o offset] [-s size] [-P fillpatt] [-S geomfile]
[-w -r -d -n -I -B -t -T -g -G -R -E]
[--F fdiskfile] [ [-v] -W {fdiskfile -}]
[-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
systems
o Create and modify an fdisk partition table on
removable 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 con-
taining the second-stage bootstrap (the active Solaris par-
tition). 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. In this mode, (x86
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System Administration Commands fdisk(1M)
only) when creating an entry for a non-EFI partition on a
disk that is larger than 2 TB (terabytes), fdisk warns that
the maximum size of the partition is 2 TB. Under these con-
ditions percentages displayed by fdisk are based on 2 TB.
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.
Note -
The third mode of operation is not currently supported for
extended partitions
When fdisk creates a partition, the space is allocated in
the fdisk partition table, but the allocated disk space is
not initialized. newfs(1M) is required to create and write
file system metadata to the new partition, and format(1M) is
required to write the VTOC or EFI/GPT metadata.
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 pro-
gram 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.
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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.
Change between Solaris and Solaris2 Partition IDs
This option allows the user to switch between the
current fdisk operating system partition identifier and
the previous one. This does not affect any data in the
disk partition and is provided for compatibility with
older software.
Edit/View extended partitions
This option provides the extended partition menu to the
user. Use the extended partition menu to add and delete
logical drives, change the sysid of the logical drives,
and display logical drive information. To commit the
changes made in the extended partition, you must return
to the main menu using the extended partition submenu
option r. There is also an option to display the list of
options that the extended partition submenu supports.
Given below is the list:
a Add a logical drive.
Use this submenu option to add a logical drive.
There are three pieces of information that are
required: The beginning cylinder, the size (in
cylinders or in human readable form - KB, MB, or
GB), and the partition ID. While specifying the
partition ID, there is an option (I) that lyou can
use to list the supported partitions.
d Delete a logical drive.
Use this submenu option to delete a logical drive.
The only input required is the number of the logi-
cal drive that is to be deleted.
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h Display the help menu.
This submenu option displays the supported opera-
tions in the extended partition submenu.
i Change the id of the logical drive.
Use this submenu option to change the system ID of
the existing logical drives. A list of supported
system IDs is displayed when you use the I option
when in this submenu.
p Display the logical drive layout.
Displays the logical drive information to stdout.
This output reflects any changes made during the
current run of the fdisk program. The changes are
not committed to the disk until return to the main
menu (using the submenu r) and choose the option to
commit the changes to the disk.
r Return to the main fdisk menu.
Exit the extended partition submenu and return to
the main menu.
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
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zero out the VTOC on the Solaris partition if the fdisk
table changes.
-b masterboot
Specify the file masterboot as the master boot program.
The default master boot program is
/usr/lib/fs/ufs/mboot.
-B
Default to one Solaris partition that uses the whole
disk. On an x86 machine, if the disk is larger than 2 TB
(terabytes), the default size of the Solaris partition
will be limited to 2 TB.
-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.
-E
Create an EFI partition that uses the entire disk.
-F fdiskfile
Use fdisk file fdiskfile to initialize table. Use of
this option will zero out the VTOC on the Solaris parti-
tion if the fdisk table changes.
The fdiskfile contains four specification lines for the
primary partitions followed by specification lines for
the logical drives. You must have four lines for the
primary partitions if there is at least one logical
drive. In this case, if the number of primary partitions
to be configured is less than four, the remaining lines
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should be filled with zeros. Each line is composed of
entries that are position-dependent, are separated by
whitespace 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 informa-
tion.
bcyl This is the cylinder where the partition
starts. If this is set to 0, fdisk will
correctly fill this in from other informa-
tion.
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 informa-
tion.
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
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other fields. For logical drives, you must
make sure that there are at least 63 free
sectors before the rsect specified for a log-
ical drive.
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 dev-
ice. 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 addi-
tion, note that fdisk will not come up in interactive
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.
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-P fillpatt
Fill disk with pattern fillpatt. fillpatt can be
decimal or hex and is used as number for constant long
word pattern. If fillpatt 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 geomfile
Set the label geometry to the content of the geomfile.
The geomfile 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 format:
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.
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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 partition
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 fdiskfile
Create an fdisk file fdiskfile from disk table. This
can be used with the -F option below.
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FILES
/dev/rdsk/c0t0d0p0 Raw device associated with the
fixed disk.
/usr/lib/fs/ufs/mboot Default master boot program.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Architecture x86 and SPARC
Availability SUNWcsu
SEE ALSO
uname(1), fmthard(1M), format(1M), newfs(1M), prtvtoc(1M),
attributes(5)
DIAGNOSTICS
Most messages will be self-explanatory. The following may
appear immediately after starting the program:
Fdisk: cannot open
This indicates that the device name argument is not
valid.
Fdisk: unable to get device parameters for 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 ini-
tially 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.
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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.
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