diskutil
diskutil manipulates the volume-level structure of local disks. It provides information about, and allows the administration of, the partitioning scheme of disks, optical discs, and AppleRAID sets.
Mac OS X man page
diskutil(8) BSD System Manager's Manual diskutil(8)
NAME
diskutil -- Modify, verify and repair local disks.
SYNOPSIS
diskutil [quiet] verb [options]
DESCRIPTION
diskutil manipulates the volume-level structure of local disks. It pro-
vides information about, and allows the administration of, the partition-
ing scheme of disks, optical discs, and AppleRAID sets.
VERBS
Each verb is listed with its description and individual arguments.
list [-plist | device]
List disks. If no argument is given, then all disks and all
of their partitions are listed.
If -plist is specified, then a property list will be emitted
instead of the normal user-readable output. If a device is
specified, then instead of listing all families of whole disks
and their partitions, only one such family is listed. In that
case, specifying either the whole disk or any of its slices
will work. The -plist and device arguments may not both be
specified at the same time.
A script could interpret the results of the diskutil list
-plist output and use diskutil info -plist as well as diskutil
listFilesystems -plist for more detailed information.
See the DEVICES section below for the various forms that the
device specification may take for this and all of the other
diskutil verbs.
The top-to-bottom appearance of partitions in diskutil list
always indicates the on-disk ordering. BSD disk identifiers
may, in certain circumstances, not appear in slice-numerical
order when viewed this way. This is normal and is likely the
result of a recent partition map editing operation in which
volumes were kept mounted.
info | information [-plist] device
Get detailed information about a specific whole disk or parti-
tion. If -plist is specified, then a property list instead of
the normal user-readable output will be emitted.
listFilesystems [-plist]
Show the file system personalities available for formatting in
diskutil when using the erasing and partitioning verbs. This
is a subset of the complete set of personalities exported by
the various filesystem bundles that may be installed in the
system. Also shown are some shortcut aliases for common per-
sonalities. See the FORMAT section below for more details.
If -plist is specified, then a property list instead of the
normal user-readable output will be emitted.
unmount | umount [force] device
Unmount a single volume. Force will force-unmount the volume
(less kind to any open files; see also umount (8)).
unmountDisk | umountDisk [force] device
Unmount an entire disk (all volumes). Force will force-
unmount the volumes (less kind to any open files; see also
umount (8)).
eject device
Eject a disk. Media will become offline for the purposes of
being a data store for file systems or being a member of con-
structs such as software RAID or direct data. Additionally,
removable media will become eligible for safe manual removal;
automatically-removable media will begin its physical (motor-
ized) eject sequence.
mount [readOnly] [-mountPoint path] device
Mount a single volume. If readOnly is specified, then the
file system is mounted read-only, even if the volume's under-
lying file system and/or device and/or media supports writing;
even the super-user may not write to it; this is the same as
the rdonly option to mount (8). If a -mountPoint is speci-
fied, then that path, rather than the standard path of /Vol-
umes/VolumeName, will be used as the view into the volume file
content; a directory at that path must already exist.
mountDisk device
Mount an entire disk (all mountable volumes).
rename | renameVolume device name
Rename a volume. Volume names are subject to file system-spe-
cific alphabet and length restrictions.
enableJournal device
Enable journaling on an HFS+ volume. This works whether or
not the volume is currently mounted (the volume is temporarily
mounted if necessary). Ownership of the affected disk is
required.
disableJournal [force] device
Disable journaling on an HFS+ volume. This normally works
whether or not the volume is currently mounted (the volume is
temporarily mounted if necessary). If the force option is
specified, then journaling is disabled directly on disk; in
this case, the volume must not be mounted. Ownership of the
affected disk is required.
moveJournal external|internal [journalDevice] device
external will create a 512MB Apple_Journal partition out of
journalDevice and an HFS+ partition will be created out of the
remaining space if available; journalDevice must be a parti-
tion, not a whole-disk. The journal for device will then be
moved externally onto the newly created Apple_Journal parti-
tion.
internal will move the journal for device back locally.
enableOwnership device
Enable ownership of a volume. The on-root-disk Volume Data-
base at /var/db/volinfo.database is manipulated such that the
User and Group ID settings of files, directories, and links
(file system objects, or "FSOs") on the target volume are
taken into account.
This setting for a particular volume is persistent across
ejects and injects of that volume as seen by the current OS,
even across reboots of that OS, because of the entries in this
OS's Volume Database. Note thus that the setting is not kept
on the target disk, nor is it in-memory.
For some locations of devices (e.g. internal hard disks), con-
sideration of ownership settings on FSOs is the default. For
others (e.g. plug-in USB disks), it is not.
When ownership is disabled, Owner and Group ID settings on
FSOs appear to the user and programs as the current user and
group instead of their actual on-disk settings, in order to
make it easy to use a plug-in disk of which the user has phys-
ical possession.
When ownership is enabled, the Owner and Group ID settings
that exist on the disk are taken into account for determining
access, and exact settings are written to the disk as FSOs are
created. A common reason for having to enable ownership is
when a disk is to contain FSOs whose User and Group ID set-
tings, and thus permissions behavior overall, is critically
important, such as when the plug-in disk contains system files
to be changed or added to.
See also the vsdbutil command. Running as root is required.
disableOwnership device
Disable ownership of a volume. See enableOwnership above.
Running as root is required.
verifyVolume device
Verify the data structure of a volume (e.g. fsck). Ownership
of the affected disk is required.
repairVolume device
Repair the data structure of a volume (e.g. fsck). Ownership
of the affected disk is required.
verifyPermissions [-plist] device
Verify the permissions of a Mac OS X boot volume. The data
that guides the permissions verification is written during the
installation process.
repairPermissions [-plist] device
Repair the permissions of a Mac OS X boot volume. The data
that guides the permissions repair is written during the
installation process. Ownership of the affected disk is
required.
eraseDisk format name [[APM]Format | [MBR]Format | [GPT]Format] device
Erase an existing disk, removing all volumes and writing out a
new partitioning scheme containing one new empty filesystem
volume. If the partitioning scheme is not specified, then an
appropriate one for the current machine is chosen. Format is
discussed below in the section for the partitionDisk verb.
Ownership of the affected disk is required.
eraseVolume format name device
Erase an existing volume or write out a new empty filesystem
if there was none. Format is discussed below in the section
for the partitionDisk verb. Ownership of the affected disk is
required.
eraseOptical [quick] device
Erase optical media (CD/RW, DVD/RW, etc.). Quick specifies
whether the disc recording system software should do a full
erase or a quick erase. Ownership of the affected disk is
required.
zeroDisk device
Erase a device, writing zeros to the media. The device can be
a whole-disk or a partition. In either case, in order to be
useful again, zero'd whole-disks will need to be partitioned,
or zero'd partitions will need to be erased (newfs'd), e.g. by
using the partitionDisk or eraseDisk verbs. If you desire a
more sophisticated erase algorithm or if you need to erase
only free space not in use for files, use the secureErase
verb. Ownership of the affected disk is required.
randomDisk [times] device
Erase a whole disk, writing random data to the media. Times
is the optional (defaults to 1) number of times to write ran-
dom information. The device can be a whole-disk or a parti-
tion. In either case, in order to be useful again, randomized
whole-disks will need to be partitioned, or randomized parti-
tions will need to be erased (newfs'd), e.g. by using the
partitionDisk or eraseDisk verbs. If you desire a more
sophisticated erase algorithm or if you need to erase only
free space not in use for files, use the secureErase verb.
Ownership of the affected disk is required.
secureErase [freespace] level device
Erase, using a secure method, either a whole-disk (including
any and all partitions), or, only the free space (not in use
for files) on a currently-mounted volume. Erasing a whole-
disk will leave it useless until it is partitioned again.
Erasing freespace on a volume will leave it exactly as it was
from an end-user perspective, with the exception that it will
not be possible to recover deleted files or data using utility
software. If you need to erase all contents of a partition
but not its hosting whole-disk, use the zeroDisk or randomDisk
verbs. Ownership of the affected disk is required.
Level should be one of the following:
o 0 - Single-pass zero-fill erase.
o 1 - Single-pass random-fill erase.
o 2 - US DoD 7-pass secure erase.
o 3 - Gutmann algorithm 35-pass secure erase.
o 4 - US DoE algorithm 3-pass secure erase.
partitionDisk device [numberOfPartitions] [[APM]Format | [MBR]Format |
[GPT]Format] [part1Format part1Name part1Size part2Format
part2Name part2Size part3Format part3Name part3Size ...]
(re)Partition a disk, removing all volumes. All volumes on
this disk will be destroyed. The device parameter specifies
which whole disk is to be partitioned. The optional
numberOfPartitions parameter specifies the number of parti-
tions to create; if given then the number of parameter
triplets (see below) is expected to match; else, the number of
triplets alone given will determine the number of partitions
created.
The optional partitioning scheme parameter forces a particular
partitioning scheme; if not specified, a suitable default is
chosen. They are:
o [APM]Format specifies that an Apple Partition Map
scheme should be used. This is the traditional
Apple partitioning scheme used to start up a Pow-
erPC-based Macintosh computer, to use the disk as a
non-startup disk with any Mac, or to create a multi-
platform compatible startup disk.
o [MBR]Format specifies that a Master Boot Record
scheme should be used. This is the DOS/Windows-com-
patible partitioning scheme.
o [GPT]Format specifies that a GUID Partitioning Table
scheme should be used. This is the partitioning
scheme used to start up an Intel-based Macintosh
computer.
For each partition, a triplet of the desired filesystem for-
mat, volume name, and size must be specified. Several other
diskutil verbs allow these triplets as well (and for them, the
numberOfPartitions parameter is also optional). The triplets
must be as follows:
o Format names are of the form HFS+, MS-DOS, etc.; a
list of formatable filesystems and common aliases is
available from the listFilesystems verb. You can
specify Free Space to skip an area of the disk.
Format guides diskutil both in what partition type
to set for the partitions (slices) as well as what
filesystem structures to lay down therein, e.g. with
the appropriate newfs_* (8).
o Names are the initial volume names; they must con-
form to filesystem-specific restrictions. If a name
of %noformat% is specified, then the partition is
left blank such that the partition space is carved
out, the partition type is set according to the
filesystem format name, the partition space is par-
tially erased, but a filesystem structure is not
laid down; this is useful in certain cases e.g. when
setting up ZFS pools. For Free Space triplets,
names are ignored but dummy names must be present.
o Sizes are floating point numbers followed by a let-
ter or percent sign as described in the sizes sec-
tion at the end of this page (e.g. 165536000B,
55.3T, 678M, 75%, R).
The last partition may be lengthened to the end of the disk.
You can specify an exact size for your last partition by spec-
ifying it as the penultimate triplet and specifying an addi-
tional (last) triplet as Free Space.
Ownership of the affected disk is required.
resizeVolume device size [numberOfPartitions] [part1Format part1Name
part1Size part2Format part2Name part2Size part3Format
part3Name part3Size ...]
Non-destructively resize a volume. You may increase or
decrease its size.
A size of limits will print the range of valid values for the
current filesystem.
When decreasing the size, new partitions may optionally be
created to fill the newly-freed space. To do this, specify
the numberOfPartitions, format, name, and size parameters in
the same manner as the triplet description for the
partitionDisk verb.
Resizing a volume that is currently set as the computer's
startup disk will invalidate that setting; use the Startup
Disk System Preferences panel or bless (8) to reset the
resized volume as the startup disk.
Device refers to a volume; the volume's file system must be
journaled HFS+. Valid sizes are a number followed by a capi-
tal letter multiplier or percent sign suffix as described in
the sizes section at the end of this page (e.g. 1.5T, 128M,
50%). Ownership of the affected disk is required.
splitPartition device [numberOfPartitions] [part1Format part1Name
part1Size part2Format part2Name part2Size part3Format
part3Name part3Size ...]
Destructively split a volume into multiple partitions. You
must supply a list of new partitions to create in the space of
the old partition; specify these with the numberOfPartitions,
format, name, and size parameters in the same manner as the
triplet description for the partitionDisk verb.
Device refers to a volume. Ownership of the affected disk is
required.
mergePartitions [force] format name fromDevice toDevice
Merge two or more partitions on a disk. All data on merged
partitions other than the first will be lost. The first will
be erased if it doesn't have a resizable type (e.g. JHFS+) or
if the force argument is given. Format and name apply only
when the first partition is being erased. Merged partitions
are required to be ordered sequentially on disk (see diskutil
list for the actual on-disk ordering). Ownership of the
affected disk is required.
appleRAID raidVerb [...]
AppleRAID verbs can be used to create, manipulate and destroy
AppleRAID volumes (Software RAID). AppleRAID supports three
basic types of RAID sets:
o "stripe" - Striped Volume (RAID 0)
o "mirror" - Mirrored Volume (RAID 1)
o "concat" - Concatenated Volume (Spanning)
Of these three basic types, only the "mirror" type increases
fault-tolerance. Mirrors may have more than two disks to fur-
ther increase their fault-tolerance. Striped and concaten-
tated volumes are, in fact, more vulnerable to faults than
single disk volumes.
From these basic types, "stacked" or "nested" RAID volumes can
be created. Stacked RAID sets that make use of mirrored RAID
sets are fault-tolerant. For example, these are some of the
more common combinations of stacked RAID sets:
o RAID 50 - A striped RAID set of hardware RAID 5
disks.
o RAID 10 - A striped RAID set of mirrored RAID sets.
o RAID 0+1 - A mirrored RAID set of striped RAID sets.
o Concatenated Mirror - A concatenation of mirrored
RAID sets.
When creating new RAID sets or adding disks, if possible, it
is better to specify the entire disk instead of a partition on
that disk. This allows the software to reformat the entire
disk using the most current partition layouts. When using
whole disks, the type of partitioning used is selected based
on the platform type (PPC = APMFormat, Intel = GPTFormat).
GPT and APM partition formats cannot be mixed in the same RAID
set.
In addition to whole disk and partition device names,
AppleRAID uses UUIDs to refer to existing RAID sets and their
members. Existing RAID sets may also be specified by mount
point (e.g. /Volume/raidset). In many cases, using the UUID
for the device argument is preferred because disk device names
may change over time when disks are added, disks are removed
or when the system is rebooted. If RAID members have been
physically disconnected from the system or are no longer
responding, you must use the member's UUID as the command
argument. Messages in the system log will refer to RAID sets
and their member disks by UUID. For more information on spec-
ifying device arguments see the "DEVICES" section below.
AppleRAID is not a replacement for backing up your data.
Backups should be always be performed on a regular basis and
before modifying any RAID set using these commands.
The following is a list of raidVerb sub-verbs with their
descriptions and individual arguments.
list [UUID]
Display AppleRAID volumes with current status and
associated member disks. If UUID is specified,
only list that RAID. diskutil listRAID is a depre-
cated synonym for diskutil appleRAID list.
create mirror|stripe|concat setName format devices ...
Create a new RAID set consisting of multiple disks
and/or RAID sets. setName is used for both the
name of the created RAID volume and the RAID set
itself (as displayed in list). e.g. 'diskutil cre-
ateRAID stripe MyArray JHFS+ disk1 disk2 disk3
disk4'. Ownership of the affected disks is
required. diskutil createRAID is a deprecated syn-
onym for diskutil appleRAID create.
delete raidVolume
Destroy an existing RAID set. If the RAID set is a
mirror with a resizable filesystem, delete will
attempt to convert each of the member partitions
back into a non-RAID volume while retaining the
contained filesystem. For concatenated RAID sets
with a resizable filesystem, delete will attempt to
shrink the filesystem to fit on the first member
partition and convert that to a non-RAID volume.
Ownership of the affected disks is required.
diskutil destroyRAID is a deprecated synonym for
diskutil appleRAID delete.
repairMirror raidVolume newDevice
Repair a degraded mirror by replacing a broken or
missing member. Broken devices in the mirrored set
can also be rebuilt by specifying newDevice. When
replacing members of a mirrored set, the new disk
must be the same size or larger than the existing
disks in the RAID set. Ownership of the affected
disk is required. diskutil repairMirror is a dep-
recated synonym for diskutil appleRAID
repairMirror.
add type newDevice raidVolume
Add a new member or hot spare to an existing RAID
set. Type can be either member or spare. New
disks are added live, the RAID volume does not need
to be unmounted. Mirrored volumes support adding
both members and hot spares, concatenated volumes
only support adding members. When adding to a mir-
rored RAID set, the new disk must be the same size
or larger than the existing disks in the RAID set.
Adding a hot spare to a mirror will enable autore-
building for that mirror. Adding a new member to a
concatenated RAID set appends the member and
expands the RAID volume. Ownership of the affected
disk is required. diskutil addToRAID is a depre-
cated synonym for diskutil appleRAID add.
remove oldDevice raidVolume
Remove a member or spare from an existing RAID set.
Old disks are removed live, the RAID volume does
not need to be unmounted. For missing devices,
oldDevice must be the device's UUID. Online mirror
members with a resizable filesystem will be con-
verted to non-RAID volumes, spare and offline mem-
bers will be marked free. For concatenated RAID
sets, only the last member can be removed. For
resizable filesystems remove will first attempt to
shrink the concatenated RAID set so that the
filesystem fits on the remaining disks. Ownership
of the affected disk is required. diskutil
removeFromRAID is a deprecated synonym for diskutil
appleRAID remove.
enable mirror|concat device
Convert a non-RAID disk partition containing a
resizable filesystem (like JHFS+) into an unpaired
mirror or single disk concatenated RAID set. Disks
that were originally partitioned on Mac OS X 10.2
Jaguar or earlier or were partitioned to be Mac OS
9 compatible may not be resizable. Ownership of
the affected disk is required. diskutil enableRAID
is a deprecated synonym for diskutil appleRAID
enable.
update key value raidVolume
Update the key value parameters of an existing RAID
set. Valid keys are:
o AutoRebuild - If true, the system
attempts to rebuild degraded mirrored
volumes automatically. When looking for
devices for rebuild, AppleRAID first
looks for hot spares and then degraded
members. Use a value of "1" for true and
"0" for false.
o SetTimeout - Controls how long the system
waits (in seconds) for a missing device
before degrading a mirrored raid set.
Also controls the amount of time you have
to disconnect all devices from an
unmounted mirror without degrading it.
Ownership of the affected disk is required.
diskutil updateRAID is a deprecated synonym for
diskutil appleRAID update.
DEVICES
A device parameter to any of the above commands (except where explicitly
required otherwise) is usually any of the following:
o The disk identifier (see below). Any entry of the form of
disk*, e.g. disk1s9.
o The device node entry containing the disk identifier. Any
entry of the form of /dev/disk*, e.g. /dev/disk2.
o The volume mount point. Any entry of the form of /Volumes/*,
e.g. /Volumes/Untitled.
o The Universally Unique Identifier or UUID. Any entry of the
form of e.g. 11111111-2222-3333-4444-555555555555.
DISK IDENTIFIER
The disk identifier string variously identifies a device unit, a session
upon that device, or a partition (slice) upon that session. It may take
the form of diskU, diskUsS, diskUsQ, or diskUsQsS, where U, S, and Q are
decimal integers (possibly multi-digit), and where:
o U is the device unit. It may refer to hardware (e.g. a hard
drive, optical drive, or memory card) or a "drive" constructed
by software (e.g. an AppleRAID set or a disk image).
o Q is the session and is only included for optical media; it
refers to the number of times recording has taken place on the
currently-inserted medium (disc).
o S is the slice; it refers to a partition. Upon this partition,
the raw data that underlies a user-visible file system is usu-
ally present, but it may also contain specialized data for cer-
tain 3rd-party database programs, or data required for the sys-
tem software (e.g. EFI or booter partitions, or APM partition
map data).
Some units (e.g. floppy disks, RAID sets) contain filesystem data upon
their "whole" device instead of containing a partitioning scheme with
partitions.
Note that the forms diskUsQ and diskUsS appear the same and must be dis-
tinguished by context. For non-optical media, this two-part form identi-
fies a slice upon which (filesystem) data is stored. For optical media,
it identifies a session upon which a partitioning scheme (with its slices
with filesystems) is stored.
SIZES
Wherever a size is to be specified, you can specify absolute values as a
decimal number, possibly followed by a period and a decimal fraction,
followed without whitespace with a letter as follows:
o B is bytes (not blocks) where the multiplier is 1.
o S is 512-byte blocks (device-independent) where the multiplier
is 512.
o K is power of 10 kilobytes where the multiplier is 1000 (1 x
10^3).
o M is power of 10 megabytes where the multiplier is 1000000 (1 x
10^6).
o G is power of 10 gigabytes where the multiplier is 1000000000
(1 x 10^9).
o T is power of 10 terabytes where the multiplier is
1000000000000 (1 x 10^12).
o P is power of 10 petabytes where the multiplier is
1000000000000000 (1 x 10^15).
Additionally, in certain contexts, such as when specifying partition
triplets, the following relative forms may also be used:
o % (with a preceding number) is a percentage of the whole-disk
size.
o R (with no preceding number) specifies the remainder of the
whole-disk size after all other triplets in the group are taken
into account. It need not be in the last triplet. It must
only appear in at most one triplet in the group of triplets.
Note again that B refers to bytes and S refers to 512-byte-blocks; the
latter is useful when working with tools such as gpt (8) or df (1). Note
also that these 512-byte-blocks are BSD software blocks and not necessar-
ily the same size as the block size actually implemented by the underly-
ing hardware.
Examples: 10G (10 gigabytes), 4.23T (4.23 terabytes), 5M (5 megabytes),
25.4% (25.4 percent of whole disk size).
FORMAT
The format parameter for the erasing and partitioning verbs is the
filesystem personality name. You can determine this name by looking in a
filesystem bundle's
/System/Library/Filesystems/<fs>.fs/Contents/Info.plist or by using the
listFilesystems verb, which also lists shortcut aliases for common per-
sonalities (these shortcuts are defined by diskutil for use with it
only).
Common examples include JHFS+, MS-DOS, etc.
EXAMPLES
Erase a disk
diskutil eraseDisk UFS UntitledUFS disk3
Erase a volume
diskutil eraseVolume HFS+ UntitledHFS /Volumes/SomeDisk
Partition a disk with three partitions
diskutil partitionDisk disk3 3 HFS+ Untitled 10G UFS UntitledUFS 10G MS-
DOS DOS 10G
Partition a disk with the APM partitioning scheme
diskutil partitionDisk disk3 APM HFS+ vol1 25% Journaled HFS+ vol2 25%
Journaled HFS+ vol3 50% Free Space volX 0%
Partition a disk with the GPT partitioning scheme
diskutil partitionDisk disk3 GPT HFS+ vol1 25% MS-DOS vol2 25% HFS+ vol3
50% Free Space volX 0%
Resize a volume and create a volume after it, using all remaining space
diskutil resizeVolume /Volumes/SomeDisk 50g MS-DOS DOS 0b
Resize a volume and leave all remaining space as unused
diskutil resizeVolume /Volumes/SomeDisk 12g
Merge two partitions into a new partition
diskutil mergePartitions JHFS+ not disk1s3 disk1s5
Split a partition into three new ones
diskutil splitPartition /Volumes/SomeDisk JHFS+ vol1 12g MS-DOS vol2 8g
JHFS+ vol3 0b
Create a RAID
diskutil createRAID mirror MirroredVolume JHFS+ disk1 disk2
Destroy a RAID
diskutil destroyRAID /Volumes/MirroredVolume
Repair a damaged RAID
diskutil repairMirror /Volumes/MirroredVolume disk3
Convert volume into RAID volume
diskutil enableRAID mirror /Volumes/ExistingVolume
SEE ALSO
authopen(1), hdid(8), hdiutil(1), ufs.util(8), msdos.util(8),
hfs.util(8), drutil(1), diskarbitrationd(8), mount(8), umount(8),
newfs(8), vsdbutil(8), fsck(8)
HISTORY
The eraseDisk and partitionDisk verbs had an option to add Mac OS 9 driv-
ers (in partitions designated for that purpose); there was also a
repairOS9Permissions verb. These have been removed.
Starting with Mac OS X 10.6, the input and output notation of disk and
partition sizes use power-of-10 suffixes. In the past this has been
power-of-2, regardless of the suffix (e.g. G, Gi, GiB) used for display
or accepted as input.
Mac OS X 15 May 2009 Mac OS X
