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 structure of local disks. It provides informa-
tion about, and allows the administration of, the partitioning schemes,
layouts, and formats of disks. This includes hard disks, solid state
disks, optical discs, CoreStorage volumes, and AppleRAID sets. It gener-
ally manipulates whole volumes instead of individual files and directo-
ries.
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.
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.
activity
Continuously display system-wide disk manipulation activity as
reported by the Disk Arbitration framework until interrupted
with a signal (e.g. by typing Control-C).
This can be useful to watch system-wide activity of disks com-
ing on-line or being ejected, volumes on disks being mounted
or unmounted, volumes being renamed, etc. However, this out-
put must never be parsed; programs should become Disk Arbitra-
tion clients instead.
For debugging information, such as the monitoring of applica-
tions dissenting (attempting to deny) activities for disks for
which they have registered an interest, you must use the log-
ging features of the diskarbitrationd daemon. Programs needing
this information must become Disk Arbitration clients.
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 file system 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)). You should specify a whole disk, but all volumes
of the whole disk are attempted to be unmounted even if you
specify a partition.
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). You should
specify a whole disk, but all volumes of the whole disk are
attempted to be mounted even if you specify a partition.
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.
Moving the journal works whether or not the volume is mounted,
provided journaling is enabled on that volume. No errors are
currently supported to flag attempts to move journals on vol-
umes that do not have journaling enabled. Ownership of the
affected disk(s) is required.
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 file system data structures of a volume. The
appropriate fsck program is executed and the volume is left
mounted or unmounted at it was before the command. Ownership
of the disk to be verified is required.
repairVolume device
Repair the file system data structures of a volume. The
appropriate fsck program is executed and the volume is left
mounted or unmounted at it was before the command. Ownership
of the affected disk is required.
verifyDisk device
Verify the partition map layout of a whole disk intended for
booting or data use on a Macintosh. The checks further
include, but are not limited to, the integrity of the EFI Sys-
tem Partition, the integrity of any Core Storage Physical Vol-
ume partitions, and provisioning of space for boot loaders.
Ownership of the disk to be verified is required; it must be a
whole disk and must have a partition map.
repairDisk device
Repair the partition map layout of a whole disk intended for
booting or data use on a Macintosh. The repairs further
include, but are not limited to, the repair or creation of an
EFI System Partition, the integrity of any Core Storage Physi-
cal Volume partitions, and the provisioning of space for boot
loaders. Ownership of the affected disk is required; it must
be a whole disk and must have a partition map.
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. Ownership of the disk to be verified is
required.
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 file system
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 file system
if there was none. Format is discussed below in the section
for the partitionDisk verb. Ownership of the affected disk is
required.
reformat device
Erase an existing volume by writing out a new empty file sys-
tem of the same personality (type) and with the same volume
name. 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 [force] 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 (re)parti-
tioned, or zero'd partitions will need to be (re)formatted
with a file system, e.g. by using the partitionDisk,
eraseDisk, or eraseVolume verbs. If you desire a more sophis-
ticated erase algorithm or if you need to erase only free
space not in use for files, use the secureErase verb. The
force parameter causes best-effort, non-error-terminating,
forced unmounts and shared-mode writes to be attempted; how-
ever, this is still no guarantee against drivers which claim
the disk exclusively. In such cases, you may have to first
unmount all overlying logical volumes (e.g. CoreStorage or
AppleRAID), or, if a disk is partially damaged in just the
wrong way, even un-install a kext or erase the disk elsewhere.
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 (re)partitioned, or randomized
partitions will need to be (re)formatted with a file system,
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 file system 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 file systems (more precisely,
personalities exported by the installed file system
bundles) and common aliases is available from the
listFilesystems verb. Format guides diskutil both
in what partition type to set for the partitions
(slices) as well as what file system structures to
lay down therein, using the file system bundle's
plist's FormatExecutable setting (which usually
points to the appropriate formatter program such as
newfs_hfs (8)). You can also specify a format of
Free Space to skip an area of the disk. Addition-
ally, you can specify the partition (personality)
type manually and directly with a format of %<human-
readable partition type>% such as %Apple_HFS% or
%<GPT partition type UUID constant>% such as
%48465300-0000-11AA-AA11-00306543ECAC%; these imply
a name of %noformat% (below). Human-readable types
must be known to the system but UUID types (GPT
scheme only) can be arbitrary.
o Names are the initial volume names; they must con-
form to file system 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 file system format name, the partition space is
partially erased, but a file system structure is not
laid down with any file system's formatter program
(e.g. newfs_hfs (8)); this is useful for setting up
partitions that will contain user-defined (not nec-
essarily file system) data. For a triplet whose
format is Free Space or a directly-specified parti-
tion type, its name is ignored but a dummy name 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 [ limits | R | 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
target partition, taking into account current file system and
partition map conditions such as files in use and other
(immovable) partitions following the target.
You can grow a volume (back) to its maximum size possible,
provided no new partitions have been created that are in the
way, by specifying R for the new volume size. You should use R
instead of attempting an absolute value such as 100% because
the latter cannot count partition map overhead.
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. Data on the
first partition will be lost as well if the force argument is
given.
If force is not given, and the first partition has a resizable
file system (e.g. JHFS+), the file system will be preserved
and grown in a data-preserving manner; your format and name
parameters are ignored in this case. If force is not given,
and the first partition is not resizable, you are prompted if
you want to format. You will also be prompted to format if
the first partition has an (HFS) Allocation Block Size which
is too small to support the required growth of the first par-
tition; see the -b option for newfs_hfs (8).
If force is given, the final resulting partition is always
(re)formatted. You should do this if you wish to (re)format to
a new file system type. You will be prompted to confirm.
Format and name must always be given, but they have an effect
only when force is given.
Merged partitions are required to be ordered sequentially on
disk (see diskutil list for the actual on-disk ordering). All
partitions in the range, except for the first one, must be
unmountable. Ownership of the affected disk is required.
appleRAID | ar 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 appleRAID sub-verbs with their
descriptions and individual arguments.
list [-plist | UUID]
Display AppleRAID volumes with current status and
associated member disks. If UUID is specified,
only list the RAID set with that AppleRAID Set
UUID. If -plist is specified, then a property list
will be emitted instead of user-formatted output.
The -plist and UUID arguments may not both be spec-
ified. diskutil listRAID is a deprecated 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 file system, delete will
attempt to convert each of the member partitions
back into a non-RAID volume while retaining the
contained file system. For concatenated RAID sets
with a resizable file system, delete will attempt
to shrink the file system to fit on the first mem-
ber partition and convert that to a non-RAID vol-
ume. 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 adding a "new" disk
given as newDevice to the RAID mirror set whose
exported disk device or set UUID is given as
raidVolume. The new disk must be the same size or
larger than the existing disks in the RAID set.
After running this command, you should manually
remove the old (orphaned, failed) member(s) with
diskutil appleRAID remove. Ownership of the
affected disk is required. diskutil repairMirror
is a deprecated 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 file system 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 file systems remove will first attempt to
shrink the concatenated RAID set so that the file
system 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 file system (such as 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. Own-
ership 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.
coreStorage | cs coreStorageVerb [...]
CoreStorage verbs can be used to create, manipulate and
destroy CoreStorage volumes.
CoreStorage maintains a world of virtual disks, somewhat like
RAID, in which one can easily add or remove imported backing
store disks, as well as exported usable volumes, to or from a
pool (or several pools). This provides the user with flexibil-
ity in allocating their hardware; user or operating system
data can span multiple physical disks seamlessly, for example.
Apple CoreStorage defines four types of objects, instances of
which are uniquely represented by a UUID:
o Logical Volume Group (LVG)
o Physical Volume (PV)
o Logical Volume Family (LVF)
o Logical Volume (LV)
The Logical Volume Group (LVG) is the top or "pool" level;
zero or more may exist during any OS boot time session.
An LVG imports one or more Physical Volumes (PVs). A PV repre-
sents a device that feeds the LVG storage space; a PV is nor-
mally real media but it can be a disk image or even an
AppleRAID Set. A disk offered to be a PV must be a partition
and the encompassing scheme must be GPT.
An LVG exports zero or more Logical Volume Families (LVFs). An
LVF contains properties which govern and bind together all of
its descendant Logical Volumes (LVs). These properties provide
settings for Full Disk Encryption (FDE) (such as whether the
LVG is encrypted, which users have access, etc) and other ser-
vices.
A Logical Volume Family (LVF) exports one or more Logical Vol-
umes (LVs).
A Logical Volume (LV) exports a dev node, upon which a file
system (such as Journaled HFS+) resides.
For more information on specifying device arguments, see the
DEVICES section below.
CoreStorage is not a replacement for backing up your data.
Backups should be always be performed on a regular basis and
before modifying any CoreStorage volumes using these commands.
The following is a list of coreStorage sub-verbs with their
descriptions and individual arguments.
list [-plist | UUID]
Display a tree view of the CoreStorage world for
all current logical volume groups (LVGs) with mem-
ber disks (PVs) and exported volumes (LVFs and
LVs), with properties and status for each level.
If -plist is specified then a property list will be
emitted instead of the formatted tree output; the
UUIDs can be used with the diskutil coreStorage
information verb to get properties for the object
represented by that UUID. If UUID is specified
then an attempt is made to list only that UUID
(whatever type of CoreStorage object it may repre-
sent). The -plist and UUID arguments may not both
be specified.
info | information [-plist] UUID | device
Display properties of the CoreStorage object (LVG,
PV, LVF, or LV) associated with the given CoreStor-
age UUID or disk.
convert device [-stdinpassphrase | -passphrase [passphrase]]
Convert a regular Journaled HFS+ or Case-sensitive
Journaled HFS+ volume (must be on a partition and
within a GPT partitioning scheme) into a CoreStor-
age logical volume.
If -passphrase is specified, the on-disk bytes will
be encrypted. You will be prompted for a new
passphrase interactively, or you can specify the
passphrase on the command line. Alternatively, if
you specify -stdinpassphrase the standard input is
read for the passphrase so that a program could
execute diskutil and send the passphrase through a
pipe without having to expose it as a command-line
parameter.
The volume must be resizable (the above types are)
and also mounted. Conversion is done live and in-
place; targeting the boot volume is supported; as
much of the conversion as possible is done before
an eject or reboot is necessary.
After slightly shrinking the source volume to make
room for CoreStorage data structures at the end,
its partition type is changed to Apple_CoreStorage
and it becomes a CoreStorage Physical Volume. A
new CoreStorage Logical Volume Group is then cre-
ated with this Physical Volume as the backing
store, followed by the creation of a Logical Volume
Family and Logical Volume pair.
At this point, the new CoreStorage PV/LVG/LVF/LV
stack is ready for use, although the "old" mount-
point must first be unmounted; yet it might not be
unmountable. This will occur if the target (now the
PV) is the current boot volume.
Just before exiting, diskutil coreStorage convert
will try to unmount the target disk (which is now
the "old" mount point and the new PV). If success-
ful (target is not the boot disk), the volume now
becomes mounted from the LV. If unsuccessful (tar-
get is the boot disk), a reboot is necessary.
At this point, if no encryption was specified, all
is done. Otherwise, the bytes-on-disk will begin to
be encrypted in-place by CoreStorage automatically
"in the background" while the PV/LVG/LVF/LV stack
continues to be usable. Encryption progress may be
monitored with diskutil coreStorage list.
When encryption is finished, a passphrase will be
required the next time the LV is ejected and re-
attached. If the LV is hosting the boot volume,
this passphrase requirement will thus occur at the
next reboot.
Note that all on-disk data is not secured immedi-
ately; it is a deliberate process of encrypting all
on-disk bytes while the CoreStorage driver keeps
publishing the (usable) LVG/LV.
Ownership of the affected disk is required.
revert device | lvUUID [-stdinpassphrase] | [-passphrase
passphrase] | [-recoverykeychain file]
Convert a CoreStorage logical volume back to its
native type. The volume must have been created by
means of conversion, e.g. with diskutil coreStorage
convert.
If the volume was not created with a passphrase,
then simple ownership of the affected disk is
required; otherwise, a passphrase must be supplied,
either interactively or via one of the parameters.
create | createLVG lvgName devices ...
Create a CoreStorage logical volume group. The
disks specified will become the (initial) set of
physical volumes; more than one may be specified.
You can specify partitions (which will be re-typed
to be Apple_CoreStorage) or whole-disks (which will
be partitioned as GPT and will contain an
Apple_CoreStorage partition). The resulting LVG
UUID can then be used with createVolume below. All
existing data on the drive(s) will be lost. Owner-
ship of the affected disk is required.
delete | deleteLVG lvgUUID | lvgName
Delete a CoreStorage logical volume group. All log-
ical volume families with their logical volumes are
removed, the logical volume group is destroyed, and
the now-orphaned physical volumes are erased and
partition-typed as Journaled HFS+.
createVolume | createLV lvgUUID | lvgName type name size
[-stdinpassphrase | -passphrase [passphrase]]
Export a new logical volume family, with a new log-
ical volume under it, out of a CoreStorage logical
volume group. Type is the file system personality
to initialize on the new logical volume. Valid
types are Journaled HFS+ or Case-sensitive Jour-
naled HFS+ or their aliases. Size is the amount of
space to allocate from the parent LVG. It is given
in the same manner as the triplet description for
the partitionDisk verb, and you can also specify
with % a percentage of the current size of the LVG.
If -passphrase or -stdinpassphrase is specified, in
the same manner as with diskutil coreStorage
convert above, on-disk data will be stored in an
encrypted form as the Logical Volume is filled;
otherwise, the data will remain plain.
deleteVolume | deleteLV lvUUID | device
Remove an exported logical volume (and its logical
volume family as appropriate) from a CoreStorage
logical volume group. Any data on that logical vol-
ume will be lost. This operation will thus result
in an increase in free space in the logical volume
group.
It is assumed that the logical volume is used as a
backing store for a file system; therefore, an
unmount attempt is made which must suceeed before
the removal of the logical volume is done.
encryptVolume | encryptLV lvUUID | device [-stdinpassphrase] |
[-passphrase passphrase]
Begin a live background process of encrypting the
on-disk backing bytes of an existing plain
CoreStorage logical volume (LV).
That is, the on-disk bytes that are backing the
user data are all visited, read, and re-written in
an encrypted form; this process can take a long
time (minutes to hours). This process continues
seamlessly across reboots. The logical volume
remains usable at all times. When this command
returns, the operation will be ongoing; you can
check progress with diskutil coreStorage list.
The entire logical volume family (LVF) is affected
since all LVs in an LVF share the same encryption
settings.
Any new user data written while this background
operation is in progress will be in encrypted form.
Specifying -passphrase or -stdinpassphrase or
interactively entering a passphrase is mandatory;
you do so in the same manner as with diskutil
coreStorage convert above.
decryptVolume | decryptLV lvUUID | device [-stdinpassphrase] |
[-passphrase passphrase]
Begin a live background process of decrypting the
on-disk backing bytes of an existing encrypted
CoreStorage logical volume (LV). Bytes are read,
decrypted, and written back to disk in plain form.
The LV must be unlocked before beginning this oper-
ation.
Like as in diskutil coreStorage encryptVolume
above, all on-disk bytes are visited and converted,
the process is seamless across reboots, the logical
volume remains usable at all times, the entire log-
ical volume family (LVF) is affected, any new user
data written will be in plain form, and the opera-
tion will be ongoing when this command returns.
Specifying -passphrase or -stdinpassphrase or
interactively entering a passphrase is mandatory;
you do so in the same manner as with diskutil
coreStorage convert above.
unlockVolume | unlockLV lvUUID [-stdinpassphrase] |
[-passphrase passphrase] | [-recoverykeychain file]
Unlock a logical volume and file system, causing it
to be attached and mounted.
Data is now accessible in plain form to the file
system and applications; the on-physical-disk back-
ing bytes remain in encrypted form.
The locked state means that the CoreStorage driver
has not been given authentication information (a
passphrase) to interpret the encrypted bytes on
disk and thus export a dev node. This verb unlocks
a logical volume family (LVF) and its logical vol-
umes (LVs) by providing that authentication; as the
LVs thus appear as dev nodes, any file systems upon
them are automatically mounted.
To "re-lock" the volume, make it offline again by
ejecting it, e.g. with diskutil eject.
Credentials must be supplied. You must either enter
a passphrase interactively, specify one of the
-passphrase or -stdinpassphrase parameters in the
same manner as with diskutil coreStorage convert
above, or specify that a recovery keychain file be
used.
You can specify -recoverykeychain with a path to a
keychain file. The keychain must be unlocked (see
security (1)).
changeVolumePassphrase | passwd lvUUID [-recoverykeychain
file] [-oldpassphrase oldpassphrase]
[-newpassphrase newpassphrase] [-stdinpassphrase]
Change the passphrase of an existing encrypted vol-
ume. It need not be unlocked nor mounted. The
parameters, while variously optional, must be given
in the above order.
You must authenticate either via the -oldpassphrase
parameter, via the -stdinpassphrase parameter (with
newline or eof-terminated data given to stdin), or
via an interactive prompt (if no parameters are
given), in the same manner as diskutil coreStorage
convert above. Alternatively, you can authenticate
by specifying -recoverykeychain with a path to a
keychain file.
A new passphrase must be supplied, again via one of
the three methods above (interactive,
-newpassphrase, or -stdinpassphrase).
If you are supplying both the old and new
passphrases via stdin, they must be separated with
a newline character.
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
positive 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 file system 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 (file system) data is stored. For optical media,
it identifies a session upon which a partitioning scheme (with its slices
with file systems) is stored.
SIZES
Wherever a size is supplied as an output, it is always presented as a
base-ten approximation with one decimal digit and a base-ten SI multi-
plier, often accompanied by a precise count in bytes. Scripts should
refrain from parsing the normal output and use the -plist option instead.
Wherever a size is to be supplied as an input, you can provide values in
several different ways, some absolute and some context-sensitive. All
suffixes described below are interpreted in a case-insensitive manner.
The "B" is mandatory by itself but optional when combined with an SI or
IEC multiplier.
The most common way is to specify absolute values as a decimal number,
possibly followed by a period and a decimal fraction, followed without
whitespace with a suffix as follows:
o B is bytes (not blocks) where the multiplier is 1.
o K[B] is power of ten kilobytes where the multiplier is 1000 (1
x 10^3).
o M[B] is power of ten megabytes where the multiplier is 1000000
(1 x 10^6).
o G[B] is power of ten gigabytes where the multiplier is
1000000000 (1 x 10^9).
o T[B] is power of ten terabytes where the multiplier is
1000000000000 (1 x 10^12).
o P[B] is power of ten petabytes where the multiplier is
1000000000000000 (1 x 10^15).
o E[B] is power of ten exabytes where the multiplier is
1000000000000000000 (1 x 10^18).
You can also use the following suffixes:
o S | UAM ("sectors") is 512-byte units (device-independent)
where the multiplier is always 512.
o DBS ("device block size") is the device-dependent native block
size of the encompassing whole disk, if applicable, where the
multiplier is often 512, but not always; indeed it might not be
a power of two.
o Ki[B] is power of two kibibytes where the multiplier is 1024 (1
x 2^10).
o Mi[B] is power of two mebibytes where the multiplier is 1048576
(1 x 2^20).
o Gi[B] is power of two gibibytes where the multiplier is
1073741824 (1 x 2^30).
o Ti[B] is power of two tebibytes where the multiplier is
1099511627776 (1 x 2^40).
o Pi[B] is power of two pebibytes where the multiplier is
1125899906842624 (1 x 2^50).
o Ei[B] is power of two exbibytes where the multiplier is
1152921504606846976 (1 x 2^60).
In certain contexts (such as when specifying partition triplets) you can
provide a relative value as follows:
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 among all triplets.
Note again that B refers to bytes and S and UAM refer to a constant mul-
tiplier of 512; the latter are useful when working with tools such as gpt
(8) or df (1). Note also that this multiplier is not a "block" size as
actually implemented by the underlying device driver and/or hardware, nor
is it an "allocation block", which is a file system's minimum unit of
backing store usage, often formatting-option-dependent.
Examples: 10G (10 gigabytes), 4.23tb (4.23 terabytes), 5M (5 megabytes),
4GiB (exactly 2^32 bytes), 25.4% (25.4 percent of whole disk size).
FORMAT
The format parameter for the erasing and partitioning verbs is the file
system personality name. You can determine this name by looking in a
file system 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 JHFS+ Untitled disk3
Erase a volume
diskutil eraseVolume HFS+ UntitledHFS /Volumes/SomeDisk
Partition a disk with three partitions
diskutil partitionDisk disk3 3 HFSX Name1 10G JHFS+ Name2 10G MS-DOS
NAME3 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_hfs(8), vsdbutil(8), fsck(8)
ERRORS
diskutil will exit with status 0 if successful or 1 if it cannot complete
the requested operation; this includes cases in which usage text is
printed. Before diskutil returns with status 1, it prints a message
which might include an explanation local to diskutil, an error string
from the DiskManagement or MediaKit frameworks, an underlying POSIX
error, or some combination.
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 13 June 2013 Mac OS X
Mac OS X 10.9 - Generated Thu Oct 17 07:29:48 CDT 2013