Format

Formats the disk in the specified volume to accept Windows files.

Syntax

format volume [/fs:file-system] [/v:label] [/q] [/a:UnitSize] [/c] [/x]

format volume [/v:label] [/q] [/f:size]

format volume [/v:label] [/q] [/t:tracks /n:sectors]

format volume [/v:label] [/q]

format volume [/q]

Parameters

volume : Specifies the mount point, volume name, or drive letter of the drive you want to format. If you do not specify any of the following command-line options, format uses the volume type to determine the default format for the disk.

/fs:file-system : Specifies the file system to use FAT, FAT32, or NTFS Floppy disks can use only the FAT file system.

/v:label : Specifies the volume label. If you omit the /v command-line option or use it without specifying a volume label, format prompts you for the volume label after the formatting is completed. Use the syntax /v: to prevent the prompt for a volume label. If you format more than one disk by using one format command, all of the disks will be given the same volume label. For more information about disk volume labels, click Dir, Label, and Vol in the Related Topics list.

/a:UnitSize : Specifies the allocation unit size to use on FAT, FAT32, or NTFS volumes. If you do not specify UnitSize, it is chosen based on volume size. The following table lists valid values for UnitSize.

ValueDescription

512

Creates 512 bytes per cluster.

1024

Creates 1024 bytes per cluster.

2048

Creates 2048 bytes per cluster.

4096

Creates 4096 bytes per cluster.

8192

Creates 8192 bytes per cluster.

16K

Creates 16 kilobytes per cluster.

32K

Creates 32 kilobytes per cluster.

64K

Creates 64 kilobytes per cluster.

/q : Performs a quick format. Deletes the file table and the root directory of a previously formatted volume but does not perform a sector by sector scan for bad areas. You should use the /q command-line option to format only previously formatted volumes that you know are in good condition.

/f:size : Specifies the size of the floppy disk to format. When possible, use this command-line option instead of the /t and /n command-line options. Windows accepts the following value for size:

1440 or 1440k or 1440kb or 1.44 or 1.44m or 1.44mb
1.44-MB, double-sided, quadruple-density, 3.5-inch disk

/t:tracks : Specifies the number of tracks on the disk. When possible, use the /f command-line option instead of this command-line option. If you use the /t command-line option, you must also use the /n command-line option. These two command-line options provide an alternative method of specifying the size of the disk being formatted. You cannot use the /f command-line option with the /t command-line option.

/n:sectors : Specifies the number of sectors per track. When possible, use the /f command-line option instead of this command-line option. If you use the /n command-line option, you must also use the /t command-line option. These two command-line options provide an alternative method of specifying the size of the disk being formatted. You cannot use the /f command-line option with the /n command-line option.

/c : NTFS only. Files created on the new volume will be compressed by default.

/x : Causes the volume to dismount, if necessary, before it is formatted. Any open handles to the volume will no longer be valid.

/? : Displays help at the command prompt.

Remarks

Using format at the Recovery Console

The format command, with different parameters, is available from the Recovery Console.

Administrative privileges

You must be a member of the Administrators group to format a hard drive.

Using format 

The format command creates a new root directory and file system for the disk. It can also check for bad areas on the disk, and it can delete all data on the disk. To be able to use a new disk, you must first use this command to format the disk.

Typing a volume label

After formatting a floppy disk, format displays the following message:

Volume label (11 characters, ENTER for none)?

The volume label can be a maximum of 11 characters (including spaces). If you do not want your disk to have a volume label, just press ENTER. For information about volume labels, click label in the Related Topics list.

Formatting a hard disk

When you use the format command to format a hard disk, format displays a message of the following form before attempting to format the hard disk:

WARNING, ALL DATA ON nonremovable DISK 
DRIVE x: WILL BE LOST! 
Proceed with Format (Y/N)?_ 

To format the hard disk, press Y; if you do not want to format the disk, press N. You must have Administrator rights to format a hard disk.

Unit size

FAT file systems restrict the number of clusters to no more than 65526. FAT32 file systems restrict the number of clusters to between 65527 and 4177917.

NTFS compression is not supported for allocation unit sizes above 4096.

Format messages

When formatting is complete, format displays messages showing the total disk space, any space marked as defective, and the space available for your files.

Quick formatting

You can speed up the formatting process by using the /q command-line option. Use this command-line option only if there are no bad sectors on your hard disk.

Using format with a reassigned drive or a network drive

You should not use the format command on a drive prepared by using the subst command. You cannot format disks over a network.

Format exit codes

The following table lists each exit code and a brief description of its meaning.

Exit codeDescription

0

The format operation was successful.

1

Incorrect parameters were supplied.

4

A fatal error occurred (any error other than 0, 1, or 5).

5

The user pressed N in response to the prompt "Proceed with Format (Y/N)?" to stop the process.

You can check these exit codes by using the errorlevel condition with the if batch command.

Examples

To format a new floppy disk in drive A using the default size, type:

format a:

To perform a quick format operation on a previously formatted disk in drive A, type:

format a: /q

To format a floppy disk in drive A and assign it the volume label "DATA," type:

format a: /v:DATA

Formatting legend

FormatMeaning

Italic

Information that the user must supply

Bold

Elements that the user must type exactly as shown

Ellipsis (...)

Parameter that can be repeated several times in a command line

Between brackets ([])

Optional items

Between braces ({}); choices separated by pipe (|). Example: {even|odd}

Set of choices from which the user must choose only one

Courier font

Code or program output

Command shell overview

Dir

If

Label

Vol

Subst

Command-line reference A-Z



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