format - disk partitioning and maintenance utility
format [-f command-file] [-l log-file] [-x data-file]
[-d disk-name] [-t disk-type] [-p partition-name]
[-s] [-m] [-M] [-e] [disk-list]
format enables you to format, label, repair, and analyze disks on your
system. Unlike previous disk maintenance programs, format runs under
SunOS. Because there are limitations to what can be done to the system disk
while the system is running, format is also supported within the
memory-resident system environment. For most applications, however, running
format under SunOS is the more convenient approach.
format first uses the disk list defined in data-file
if the -x option is used. format then checks for the
FORMAT_PATH environment variable, a colon-separated list of filenames
and/or directories. In the case of a directory, format searches for a
file named format.dat in that directory; a filename should be an
absolute pathname, and is used without change. format adds all disk
and partition definitions in each specified file to the working set.
Multiple identical definitions are silently ignored. If FORMAT_PATH
is not set, the path defaults to /etc/format.dat.
disk-list is a list of disks in the form c?t?d? or
/dev/rdsk/c?t?d?s?. With the latter form, shell wildcard
specifications are supported. For example, specifying /dev/rdsk/c2*
causes format to work on all drives connected to controller c2
only. If no disk-list is specified, format lists all the disks
present in the system that can be administered by format.
Removable media devices are listed only when users execute
format in expert mode (option -e). This feature is provided
for backward compatibility. Use rmformat(1) for rewritable removable
The following options are supported:
Specify which disk should be made current upon entry into
the program. The disk is specified by its logical name (for instance,
-d c0t1d0). This can also be accomplished by specifying a single
disk in the disk list.
Enable SCSI expert menu. Note this option is not
recommended for casual use.
Take command input from command-file rather than
the standard input. The file must contain commands that appear just as they
would if they had been entered from the keyboard. With this option,
format does not issue continue? prompts; there is no need to
specify y(es) or n(o) answers in the command-file. In non-interactive
mode, format does not initially expect the input of a disk selection
number. The user must specify the current working disk with the -d
disk-name option when format is invoked, or specify disk and the
disk selection number in the command-file.
Log a transcript of the format session to the
indicated log-file, including the standard input, the standard output
and the standard error.
Enable extended messages. Provides more detailed
information in the event of an error.
Enable extended and diagnostic messages. Provides
extensive information on the state of a SCSI device's mode pages,
Specify the partition table for the disk which is current
upon entry into the program. The table is specified by its name as defined in
the data file. This option can be used only if a disk is being made current,
and its type is either specified or available from the disk label.
Silent. Suppress all of the standard output. Error
messages are still displayed. This is generally used in conjunction with the
Specify the type of disk which is current upon entry into
the program. A disk's type is specified by name in the data file. This option
can only be used if a disk is being made current as described above.
Use the list of disks contained in
When you invoke format with no options or with the -e, -l,
-m, -M, or -s options, the program displays a numbered
list of available disks and prompts you to specify a disk by list number. If
the machine has more than 10 disks, press SPACE to see the next screenful of
You can specify a disk by list number even if the disk is not
displayed in the current screenful. For example, if the current screen shows
disks 11-20, you can enter 25 to specify the twenty-fifth disk on the
list. If you enter a number for a disk that is not currently displayed,
format prompts you to verify your selection. If you enter a number
from the displayed list, format silently accepts your selection.
After you specify a disk, format displays its main menu.
This menu enables you to perform the following tasks:
Run read, write, compare tests, and data purge. The data
purge function implements the National Computer Security Center Guide to
Understanding Data Remnance (NCSC-TG-025 version 2) Overwriting
Algorithm. See NOTES.
Search for backup labels.
Enable, disable, and query the state of the write cache
and read cache. This menu item only appears when format is invoked with
the -e option, and is only supported on SCSI devices.
Display the device name, the disk geometry, and the
pathname to the disk device.
Retrieve and print defect lists. This option is supported
only on SCSI
disks perform automatic defect
management. Upon using the defect
option on an IDE
receive the message:
Controller does not support defect management
or disk supports automatic defect management.
Choose the disk that will be used in subsequent
operations (known as the current disk.)
Run the fdisk(1M)
program to create a fdisk
partition for Solaris software (x86 based systems only).
Format and verify the current disk. This option is
supported only on SCSI
disks are pre-formatted by
the manufacturer. Upon using the format
option on an IDE
you receive the message:
Cannot format this drive. Please use your
manufacturer-supplied formatting utility.
Display the vendor, product name, and revision level of
the current drive.
Write a new label to the current disk.
Create and modify slices.
Exit the format menu.
Repair a specific block on the disk.
Save new disk and slice information.
Select (define) a disk type.
Read and display labels. Print information such as the
number of cylinders, alternate cylinders, heads, sectors, and the partition
Label the disk with a new eight character volume
a colon-separated list of filenames and/or directories of
disk and partition definitions. If a directory is specified, format
searches for the file format.dat in that directory.
default data file
When the format function is selected to format the Maxtor 207MB disk, the
following message displays:
Mode sense page(4) reports rpm value as 0, adjusting it to 3600
This is a drive bug that may also occur with older third party
drives. The above message is not an error; the drive will still function
Cylinder 0 contains the partition table (disk label), which can be
overwritten if used in a raw disk partition by third party software.
format supports writing EFI-compliant disk labels in
order to support disks or LUNs with capacities greater than one
terabyte. However, care should be exercised since many software components,
such as filesystems and volume managers, are still restricted to capacities
of one terabyte or less. See the System Administration Guide: Basic
Administration for additional information.
By default, on an unlabeled disk, EFI labels will be written on
disks larger than 2 TB. When format is invoked with the -e
option, on writing the label, the label type can be chosen. Booting is not
currently supported on a disk with an EFI label.
format provides a help facility you can use whenever format is expecting
input. You can request help about what information is expected by simply
entering a question mark (?) and format prints a brief
description of what type of input is needed. If you enter a ? at the
menu prompt, a list of available commands is displayed.
For SCSI disks, formatting is done with both Primary and
Grown defects list by default. However, if only Primary list is extracted in
defect menu before formatting, formatting will be done with Primary list
Changing the state of the caches is only supported on SCSI
devices, and not all SCSI devices support changing or saving the
state of the caches.
The NCSC-TG-025 algorithm for overwriting meets the
DoD 5200.28-M (ADP Security Manual) Eraser Procedures
specification. The NIST Guidelines for Media Sanitization
(NIST SP 800-88) also reference this algorithm.