cheat sheet

diskutil

Command-line front-end to Disk Utility on macOS — list, partition, format, repair, encrypt, and snapshot APFS containers, plus build and tear down software RAID volumes.

updated 05-26-2026

diskutil — macOS Disk & APFS Management

What it is

diskutil is the macOS command-line front-end to Disk Utility, shipped by Apple in every release of macOS since Tiger (10.4). It manages every layer of the storage stack: physical disks (/dev/disk0), GPT partitions, APFS containers and volumes (synthesized at /dev/disk3, /dev/disk4, …), legacy CoreStorage and HFS+ volumes, software RAID sets, encryption (FileVault and per-volume APFS), and recovery operations like verifyVolume and repairVolume. It supersedes the older fdisk, pdisk, newfs_*, and hdiutil family for everyday disk administration, though hdiutil is still the tool for creating disk images (.dmg, sparse bundles). The Windows analogue is diskpart; on Linux the equivalent surface is split across lsblk, parted, mkfs.*, cryptsetup, and mdadm.

Install

diskutil ships with macOS at /usr/sbin/diskutil — there is nothing to install. Most read-only subcommands (list, info, apfs list) work without privilege; destructive operations (eraseDisk, resizeVolume, apfs deleteContainer) require either sudo or that the target volume is currently unmounted.

bash

which diskutil
diskutil --version 2>/dev/null || diskutil | head -1

Output:

text

/usr/sbin/diskutil
Disk Utility Tool

Syntax

diskutil is a verb-first command: a top-level verb (list, info, mount, eraseDisk, apfs, ap, cs, appleRAID) plus its own arguments. The apfs and cs subcommands open their own verb namespace (e.g. diskutil apfs addVolume). Disk identifiers can be passed as disk2, /dev/disk2, a mountpoint (/), a volume name ("Macintosh HD"), or a UUID.

bash

diskutil <verb> [<verb-args>...]
diskutil <namespace> <verb> [<verb-args>...]

# Examples of identifier forms
diskutil info disk0
diskutil info /
diskutil info "Macintosh HD"
diskutil info /Volumes/Backup

Output: (none — exits 0 on success)

Essential verbs

Verb	Meaning
`list [-plist] [DEV]`	Show all disks (or one device) and their partitions/volumes
`info [-plist] DEV`	Detailed info for one device or volume
`mount DEV` / `unmount DEV`	Mount or unmount a single volume
`unmountDisk [force] DEV`	Unmount every volume on a whole disk
`eject DEV`	Eject removable media
`eraseDisk FS NAME [GPT\|MBR\|APM] DEV`	Reformat an entire disk
`eraseVolume FS NAME DEV`	Reformat a single volume
`partitionDisk DEV NUMPARTS SCHEME (FS NAME SIZE)...`	Rebuild partition map
`resizeVolume DEV SIZE [FS NAME SIZE]...`	Grow/shrink a volume
`verifyVolume DEV` / `repairVolume DEV`	First-aid checks
`verifyDisk DEV` / `repairDisk DEV`	Whole-disk first aid
`secureErase LEVEL DEV`	Multi-pass overwrite (HDD only; not for SSDs)
`apfs <verb>`	APFS-specific subcommands (see below)
`image <verb>`	Create/convert disk images (incl. ASIF on macOS 26 Tahoe)
`appleRAID <verb>`	Software-RAID subcommands
`cs <verb>`	Legacy CoreStorage subcommands
`enableJournal DEV` / `disableJournal DEV`	HFS+ journaling
`mountDisk DEV`	Mount every volume on a disk
`activity`	Streaming log of disk arrival/removal/mount events

Listing disks and volumes

diskutil list is the canonical inventory command: it walks every physical and synthesized device and prints a tree of partitions and APFS volumes. On Apple Silicon and recent Intel Macs the boot drive shows two synthesized containers — one for the sealed System volume and one for Data — because the root filesystem is split across an immutable signed snapshot and a writable Data volume.

bash

diskutil list

Output:

text

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *994.7 GB   disk0
   1:             Apple_APFS_ISC Container disk1         524.3 MB   disk0s1
   2:                 Apple_APFS Container disk3         988.8 GB   disk0s2
   3:        Apple_APFS_Recovery Container disk2         5.4 GB     disk0s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +988.8 GB   disk3
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            10.2 GB    disk3s1
   2:              APFS Snapshot com.apple.os.update-... 10.2 GB    disk3s1s1
   3:                APFS Volume Preboot                 7.4 GB     disk3s2
   4:                APFS Volume Recovery                1.0 GB     disk3s3
   5:                APFS Volume Data                    412.0 GB   disk3s5
   6:                APFS Volume VM                      20.5 KB    disk3s6

Restricting list to a single device, requesting machine-readable plist output, and asking for an external-only listing are all routine variants — the plist form is what other tools parse.

bash

diskutil list external               # external/removable disks only
diskutil list internal               # internal disks only
diskutil list physical               # skip synthesized containers
diskutil list disk0                  # one device
diskutil list -plist | plutil -convert json -o - -

Output: (truncated JSON)

json

{
  "AllDisks": ["disk0","disk0s1","disk0s2","disk0s3","disk3","disk3s1","disk3s1s1","disk3s2","disk3s3","disk3s5","disk3s6"],
  "AllDisksAndPartitions": [
    {
      "Content": "GUID_partition_scheme",
      "DeviceIdentifier": "disk0",
      "Partitions": [
        {"DeviceIdentifier":"disk0s1","Content":"Apple_APFS_ISC","Size":524288000}
      ]
    }
  ]
}

Detailed info

diskutil info is the deep-dive companion to list — it dumps every property the kernel knows about a single disk, slice, or volume, including device node, media name, SMART status, filesystem personality, mount point, owners-enabled flag, file vault state, and the UUIDs needed for fstab entries and snapshot references.

bash

diskutil info /                      # info for the booted root
diskutil info disk0                  # whole physical disk
diskutil info disk3s5                # APFS Data volume

Output (diskutil info disk0 — truncated):

text

   Device Identifier:         disk0
   Device Node:               /dev/disk0
   Whole:                     Yes
   Part of Whole:             disk0
   Device / Media Name:       APPLE SSD AP1024Z

   Volume Name:               Not applicable (no file system)
   Mounted:                   Not applicable (no file system)

   Disk Size:                 994.7 GB (994662584320 Bytes) (exactly 1942700360 512-Byte-Units)
   Device Block Size:         4096 Bytes

   Media Type:                Generic
   Protocol:                  Apple Fabric
   SMART Status:              Verified

   Device Location:           Internal
   Removable Media:           Fixed
   Solid State:               Yes
   Virtual:                   No

Pipe info -plist into plutil -extract to read one property as a script value:

bash

diskutil info -plist disk3s5 | plutil -extract VolumeUUID raw -o - -

Output:

text

4D7F1A8C-2B40-4F7B-9E12-1A2B3C4D5E6F

APFS containers and volumes

APFS (Apple File System) replaced HFS+ as the default filesystem in macOS 10.13 High Sierra. A physical partition (an "APFS Container") hosts one or more APFS volumes that all share the same free space pool — adding a volume does not require resizing. Volume roles (System, Data, Preboot, Recovery, VM, Update) and snapshots (immutable point-in-time clones) are core APFS concepts; the system boots from a signed snapshot of the System role for tamper-evidence.

bash

diskutil apfs list                   # all containers and their volumes
diskutil apfs list disk3             # one container
diskutil apfs listSnapshots /        # snapshots of the booted volume

Output (diskutil apfs list — abridged):

text

APFS Container (1 found)
|
+-- Container disk3 6F2B...
    ====================================================
    APFS Container Reference:     disk3
    Size (Capacity Ceiling):      988800487424 B (988.8 GB)
    Capacity In Use By Volumes:   431118245888 B (431.1 GB) (43.6% used)
    Capacity Not Allocated:       557682241536 B (557.7 GB) (56.4% free)
    |
    +-< Physical Store disk0s2 A8...
    |
    +-> Volume disk3s1 — Macintosh HD          (Role: System)
    +-> Volume disk3s2 — Preboot               (Role: Preboot)
    +-> Volume disk3s3 — Recovery              (Role: Recovery)
    +-> Volume disk3s5 — Macintosh HD - Data   (Role: Data)
    +-> Volume disk3s6 — VM                    (Role: VM)

Adding and removing APFS volumes

addVolume carves a new volume out of the container's free pool — no resize is needed and the operation is online. The -quota and -reserve options are how you cap a volume's growth or guarantee minimum space; without them every volume can grow to fill the container.

bash

# Add a 0-quota Scratch volume to the existing container
diskutil apfs addVolume disk3 APFS Scratch

# Add a volume with a hard cap of 50 GB
diskutil apfs addVolume disk3 APFS Builds -quota 50g

# Delete a volume by name or identifier
diskutil apfs deleteVolume Scratch

Output:

text

Will export new APFS Volume "Scratch" from APFS Container disk3
Started APFS operation on disk3
Preparing to add APFS Volume to APFS Container disk3
Creating APFS Volume
Mounting APFS Volume
Setting volume permissions
Disk from APFS operation: disk3s7
Finished APFS operation on disk3

Snapshots

APFS snapshots are read-only clones of a volume's metadata tree at a moment in time — they take essentially no space until the live volume diverges. Time Machine creates one before every backup; tmutil exposes a higher-level API but diskutil apfs is the low-level interface.

bash

diskutil apfs listSnapshots /                       # list root snapshots
diskutil apfs createSnapshot / -name pre-upgrade    # take one
diskutil apfs deleteSnapshot / -name pre-upgrade    # delete by name
diskutil apfs deleteSnapshot / -uuid 4D7F1A8C-...   # delete by UUID

Output (listSnapshots /):

text

Snapshots for disk3s1s1 (5 found)
+-- A1B2C3D4-1111-2222-3333-444455556666
|   Name:        com.apple.os.update-7F2A...
|   XID:         812345
|   Purgeable:   No
+-- B2C3D4E5-2222-3333-4444-555566667777
|   Name:        pre-upgrade
|   XID:         812400
|   Purgeable:   Yes

Container resize and rebalance

You can grow a container into adjacent free space or move space between APFS containers and a sibling HFS+/MS-DOS partition using apfs resizeContainer. The disk's GPT partition map is rewritten online when possible.

bash

# Grow disk3 (the APFS container at disk0s2) to fill all free space on disk0
diskutil apfs resizeContainer disk0s2 0

# Shrink the container to 800 GB and create a 188.8 GB MS-DOS partition after it
diskutil apfs resizeContainer disk0s2 800g MS-DOS WORK 188.8g

Output:

text

Started APFS operation
Aligning grow delta to 188,803,883,008 bytes and targeting a new physical store size of 800,000,000,000 bytes
Determined the maximum size for the targeted physical store of this APFS Container to be 988,795,719,680 bytes
Resizing APFS Physical Store from 988,800,487,424 to 800,000,000,000 bytes
Modifying partition map
Initialized /dev/rdisk0s3 as a 175 GB case-insensitive MS-DOS (FAT32) volume
Mounting disk
Finished APFS operation

Partitioning a fresh disk

partitionDisk lets you wipe a disk's partition map and rebuild it in one atomic operation. Pass the device, the number of partitions, the scheme (GPT for modern Macs, MBR for compatibility with BIOS PCs, APM only for very old PowerPC Macs), and a FS NAME SIZE triple for each partition. A size of 0 or R means "rest of disk".

bash

# Single APFS partition spanning the whole disk
sudo diskutil partitionDisk /dev/disk4 1 GPT APFS "External" 0

# Two partitions: 200 GB APFS + remainder ExFAT (for cross-platform use)
sudo diskutil partitionDisk /dev/disk4 2 GPT \
  APFS  "Mac"     200g \
  ExFAT "Shared"  0

Output:

text

Started partitioning on disk4
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk4s2 as APFS with name Mac
Initialized /dev/rdisk4s2 as a 200 GB APFS Container
Formatting disk4s3 as ExFAT (Extended Allocation Table) with name Shared
mkexfatfs 1.3.0
Creating... done.
Flushing... done.
File system created successfully.
Mounting disk
Finished partitioning on disk4

Erasing a disk or volume

eraseDisk reformats an entire device (partition map + filesystem); eraseVolume only reformats one slice. The filesystem keyword is what newfs_* understands: APFS, APFSX (case-sensitive), JHFS+ (journaled HFS+), JHFS+X (case-sensitive journaled), ExFAT, MS-DOS FAT32, Free Space. Erasing the booted volume is not allowed — boot from Recovery first.

bash

# Erase /dev/disk4 to APFS, single volume named "Photos"
sudo diskutil eraseDisk APFS "Photos" /dev/disk4

# Erase to exFAT for Windows interoperability
sudo diskutil eraseDisk ExFAT "USB" MBR /dev/disk4

# Reformat just disk4s2 without touching the partition map
sudo diskutil eraseVolume APFS "Scratch" /dev/disk4s2

Output:

text

Started erase on disk4
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk4s2 as APFS with name Photos
Initialized /dev/rdisk4s2 as a 119 GB APFS Container
Mounting disk
Finished erase on disk4

Encryption and FileVault

APFS supports per-volume hardware-accelerated encryption that is independent of FileVault on the boot drive. FileVault adds the user-keyed unlock and recovery-key flow for the system Data volume; diskutil apfs encryptVolume and the related -fileVault flag manage the lower-level conversion. The system volume's FileVault state is also surfaced by fdesetup status.

bash

# Erase an external disk to encrypted APFS, prompting for a passphrase
sudo diskutil apfs eraseDisk APFS "Secure" /dev/disk4 \
  -passphrase                # prompt interactively

# Convert an existing unencrypted APFS volume to encrypted, in place
sudo diskutil apfs encryptVolume /Volumes/Photos \
  -user disk -passphrase

# Check encryption progress / status
diskutil apfs list disk5 | grep -E "FileVault|Encryption"

# Decrypt an APFS volume (long, online operation)
sudo diskutil apfs decryptVolume /Volumes/Photos -passphrase

# Unlock an encrypted APFS volume that mounted without a key
diskutil apfs unlockVolume /Volumes/Secure -passphrase

# Lock (dismount + drop key) an unlocked volume
diskutil apfs lockVolume /Volumes/Secure

Output (status line):

text

FileVault:                 Yes (Encrypted at rest using AES-XTS)
Encryption Type:           AES-XTS
Encryption Progress:       42.7%

FileVault on the boot drive is managed by fdesetup, not diskutil, but the two tools share the same APFS volume key chain:

bash

sudo fdesetup status               # FileVault state of boot drive
sudo fdesetup enable               # turn FileVault on (will prompt)
sudo fdesetup list                 # users authorized to unlock

Output:

text

FileVault is On.

RAID with appleRAID

diskutil appleRAID builds software RAID sets — mirror (RAID 1), stripe (RAID 0), or concat (JBOD) — out of two or more disks. RAID-5 was removed in modern macOS; for parity raid you now reach for ZFS via OpenZFS, btrfs (Linux), or a hardware controller. The resulting RAID device shows up as a new /dev/diskN that you then erase to APFS or HFS+ like any other disk.

bash

# Build a mirror (RAID 1) of two external disks
sudo diskutil appleRAID create mirror "MirrorSet" APFS \
  /dev/disk5 /dev/disk6

# Build a stripe (RAID 0) for throughput
sudo diskutil appleRAID create stripe "StripeSet" APFS \
  /dev/disk5 /dev/disk6

# Show all RAID sets
diskutil appleRAID list

# Add a spare to an existing set
sudo diskutil appleRAID add spare <setUUID> /dev/disk7

# Tear down a set (does not erase member disks unless you ask)
sudo diskutil appleRAID delete <setUUID>

Output (appleRAID list):

text

AppleRAID sets (1 found)
===============================================================================
Name:                 MirrorSet
Unique ID:            7F3A1C2D-4B5E-6789-ABCD-EF0123456789
Type:                 Mirror
Status:               Online
Size:                 999.0 GB (999000000000 Bytes)
Rebuild:              manual
Device Node:          disk7
-------------------------------------------------------------------------------
#  DevNode   UUID                                  Status     Size
0  disk5s2   A1B2C3D4-...                          Online     999.0 GB
1  disk6s2   B2C3D4E5-...                          Online     999.0 GB

First aid: verify and repair

verifyVolume runs fsck_* against a volume read-only; repairVolume runs it read-write and fixes what it can. verifyDisk/repairDisk operate on the partition map. You cannot repair the booted system volume because it is mounted read-only as a sealed snapshot — boot from Recovery (⌘R) and run from there for system-volume repairs.

bash

diskutil verifyVolume /                  # read-only check of booted volume
sudo diskutil verifyVolume disk4s2       # check external APFS volume
sudo diskutil repairVolume disk4s2       # attempt repairs
sudo diskutil verifyDisk disk4           # check partition map
sudo diskutil repairDisk disk4           # repair partition map

Output (verifyVolume):

text

Started file system verification on disk4s2 USB
Verifying file system
Performing fsck_apfs -n -x /dev/rdisk4s2
Checking the container superblock
Checking the EFI jumpstart record
Checking the space manager
Checking the object map
Checking the snapshot metadata tree
Checking the snapshot metadata
Checking volume
Checking the object map
Checking the fsroot tree
Checking the extent ref tree
Verifying allocated space
The volume /dev/rdisk4s2 appears to be OK.
Finished file system verification on disk4s2 USB

Secure erase

secureErase overwrites the device with one or more passes of zeros/random data. It is intended only for spinning hard disks — modern SSDs (every Apple-Silicon Mac, every recent Intel Mac) implement wear-levelling and over-provisioning that make a multi-pass overwrite both useless and harmful (wears the flash). For SSDs, the right approach is whole-disk APFS encryption from day one, then diskutil eraseDisk to destroy the key.

bash

# Level 0 = single-pass zero, 1 = US DoE, 2 = 7-pass DoD, 3 = 35-pass Gutmann
sudo diskutil secureErase 0 /dev/disk4       # spinning disk only
sudo diskutil secureErase freespace 0 /      # zero only the free space (any disk)

Output:

text

Started erase on disk4
0%..10%..20%..30%..40%..50%..60%..70%..80%..90%..100%
Finished erase on disk4

Live disk events

diskutil activity streams disk arrival, departure, and mount events in real time — handy when you are debugging an external dock, troubleshooting why a USB stick disappears, or scripting an auto-mount workflow.

bash

diskutil activity

Output:

text

***DiskAppeared ('disk4', DAVolumePath = '', DAVolumeKind = '', DAVolumeName = '')
***DiskAppeared ('disk4s1', DAVolumePath = '', DAVolumeKind = 'msdos', DAVolumeName = 'EFI')
***DiskAppeared ('disk4s2', DAVolumePath = '', DAVolumeKind = 'apfs', DAVolumeName = '')
***DiskAppeared ('disk5', DAVolumePath = '', DAVolumeKind = 'apfs', DAVolumeName = 'USB')
***DiskMountApproval ('disk5', id = 0xXXXX) Approving
***DiskDescriptionChanged ('disk5', DAVolumePath = 'file:///Volumes/USB/')
^C

diskutil vs other tools

The classic Unix disk tools still exist on macOS but each is now a narrower slice of what diskutil covers.

Tool	What it does	When to prefer over `diskutil`
`diskutil`	Disks, partitions, APFS, RAID, FileVault, repair	The default for everything
`fdisk`	MBR partition tables on raw block devices	Almost never — only for legacy BIOS targets
`gpt`	GPT partition tables only	Scripting low-level GPT entries the Apple way won't do
`newfs_apfs`, `newfs_hfs`, `newfs_exfat`, `newfs_msdos`	Filesystem creation primitives	Already invoked under the hood by `eraseDisk`
`hdiutil`	Create, mount, attach, convert disk images (`.dmg`, `.sparsebundle`, `.iso`)	Always for disk images — `diskutil` does not touch them
`fsck_apfs` / `fsck_hfs`	Filesystem integrity check primitives	Already invoked by `repairVolume`; call directly when you need `-y` or `-l` flags
`mount` / `umount`	Generic POSIX mount syscalls	When you need non-standard mount options (`noowners`, `nodev`)
`mount_apfs`, `mount_smbfs`, `mount_nfs`	Per-filesystem mount helpers	When mounting a snapshot or network share
`dd`	Raw block copy	Cloning bit-for-bit images outside the APFS model
`asr`	Apple Software Restore (block/file-level imaging)	Cloning a bootable APFS volume from a snapshot to another disk

Common pitfalls

Erasing the booted volume fails by design — you cannot reformat / while it is mounted. Boot from Recovery (⌘R on Intel, hold the power button on Apple Silicon) or another disk first.
secureErase on an SSD wears the flash and does not actually overwrite cells — wear-levelling routes writes elsewhere. Use whole-disk encryption from day one and destroy the key with eraseDisk instead.
apfs deleteContainer is destructive but does not require --force — every volume inside the container vanishes immediately. Always re-read diskutil list and have a backup before pulling the trigger.
Mounting a snapshot is read-only and requires the parent volume's mount point — mount_apfs -s <snapshot-name> /System/Volumes/Data /mnt is the form; you cannot diskutil mount a snapshot directly.
External Time Machine APFS disks created by macOS contain a hidden "Backups" volume — eraseDisk from the GUI sometimes leaves the role volume behind; use eraseDisk from the command line on the parent /dev/diskN to get a clean slate.
diskutil accepts a mountpoint as a disk identifier — diskutil unmount /Volumes/USB works, but if the mountpoint name contains spaces you must quote it. Prefer the device identifier in scripts.
Resizing an APFS container into an adjacent HFS+ partition refuses if the HFS+ slice has data — resizeContainer only consumes free space or destroys partitions it is told to via the trailing FS NAME SIZE triple.
diskutil apfs encryptVolume runs in the background — the command returns instantly. diskutil apfs list shows Encryption Progress: NN% while it converts. Do not eject the disk.
Apple_APFS_ISC and Apple_APFS_Recovery partitions are critical on Apple Silicon Macs — touching disk0s1 or disk0s3 with eraseDisk or partitionDisk will brick the machine. Always confirm the target identifier before destructive verbs.
enableJournal/disableJournal is HFS+ only — APFS has no on-disk journal in the HFS+ sense; the equivalent is APFS's copy-on-write metadata. Don't try to disable journaling for "performance" on APFS.

Real-world recipes

Format a fresh external drive as encrypted APFS

A common one-step setup for a new USB-C SSD: wipe it, write a GPT partition map, create an encrypted APFS container with a single volume named Backup, and mount it.

bash

# 1. Identify the new disk (look at "external, physical")
diskutil list external

# 2. Erase to encrypted APFS — passphrase prompt is interactive
sudo diskutil apfs eraseDisk APFS Backup /dev/disk5 -passphrase

# 3. Verify
diskutil apfs list | grep -E "Container|Volume"

Output:

text

Started APFS operation on disk5
Unmounting Volumes
Erasing
...
Finished APFS operation on disk5
+-- Container disk6 7F2A...
+-> Volume disk6s1 — Backup (Role: No specific role)

Snapshot-backed rollback before a system upgrade

Take a named APFS snapshot before installing a new tool, run the change, and mount the snapshot read-only to diff against if something breaks.

bash

# 1. Pre-snapshot
sudo diskutil apfs createSnapshot / -name pre-brew-upgrade

# 2. Make the risky change
brew upgrade

# 3. Mount the snapshot read-only at /mnt/snap to compare
sudo mkdir -p /mnt/snap
sudo mount_apfs -s pre-brew-upgrade /System/Volumes/Data /mnt/snap

# 4. Diff a directory
diff -r /mnt/snap/usr/local /usr/local | head -20

# 5. Done — unmount and (optionally) delete the snapshot
sudo umount /mnt/snap
sudo diskutil apfs deleteSnapshot / -name pre-brew-upgrade

Output:

text

Started APFS operation on disk3s1
Snapshotting APFS Volume "Macintosh HD" and storing the snapshot with name "pre-brew-upgrade"
Created snapshot with XID 812400
Finished APFS operation on disk3s1

Build a striped scratch volume on two USB SSDs

For temporary high-throughput work (video transcodes, build artefacts), stripe two external SSDs into a single throwaway volume.

bash

# Wipe both disks first so they have no live data
sudo diskutil unmountDisk force /dev/disk5
sudo diskutil unmountDisk force /dev/disk6

# Stripe + APFS
sudo diskutil appleRAID create stripe Scratch APFS /dev/disk5 /dev/disk6

# Confirm
diskutil list | grep -A2 "Scratch"

Output:

text

Started RAID operation on disk5
Unmounting disk5
Repartitioning disk5
...
Finished RAID operation
/dev/disk8 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   1:                APFS Volume Scratch                 998.0 GB   disk8s1

Create an ASIF disk image (macOS 26 Tahoe)

ASIF is a new sparse disk image format introduced in macOS 26 Tahoe that achieves near-native read/write speeds (multi-GB/s on Apple Silicon) and stores efficiently regardless of the host filesystem. Unlike UDSP sparse-bundle or UDIF images created with hdiutil, ASIF images are made through diskutil image create. They are the recommended format for VM disks and developer scratch images on Tahoe and later, and are not back-portable to Sequoia or earlier.

bash

# Create a 100 GB blank ASIF image with a single APFS volume named "VM"
diskutil image create blank --format ASIF --size 100G \
  --volumeName VM ~/Images/dev-vm.asif

# Convert an existing image to ASIF
diskutil image create from ~/Images/old.dmg --format ASIF \
  ~/Images/converted.asif

# Attach and detach like any other disk image
hdiutil attach ~/Images/dev-vm.asif
hdiutil detach /dev/disk7

Output:

text

Started image operation
Creating ASIF image
Initialized /dev/rdiskN as a 100 GB APFS Container
Created /Users/alice/Images/dev-vm.asif
Finished image operation

ASIF is currently only available in Tahoe's Disk Utility and via diskutil image; older releases still need hdiutil create -format UDSP (or UDRW) for sparse images.

One-shot script: clone a USB stick to an APFS image

Use hdiutil (the disk-image cousin of diskutil) to read a USB stick into a sparse .dmg, then mount it back on demand. diskutil itself does not make images — but the pair is a natural pipeline.

bash

# 1. Find source
diskutil list external

# 2. Create a read-only sparse image
sudo hdiutil create -srcdevice /dev/disk5 \
  -format UDSP \
  -o ~/Backups/usb-stick.sparseimage

# 3. Later: attach for read-only inspection
hdiutil attach -readonly ~/Backups/usb-stick.sparseimage

# 4. Unmount when done
hdiutil detach /dev/disk7

Output:

text

Reading Protective Master Boot Record (MBR : 0)…
Reading GPT Header (Primary GPT Header : 1)…
...
created: /Users/alice/Backups/usb-stick.sparseimage

Find which disk a path lives on

Map an arbitrary path back to its /dev/diskN identifier — useful when piping into other tools that take device nodes.

bash

df -h /Users/alice/Movies | awk 'NR==2{print $1}'
diskutil info /Users/alice/Movies | awk -F': +' '/Device Node/{print $2}'

Output:

text

/dev/disk3s5
/dev/disk3s5

Repair a flaky external drive end-to-end

When an external disk starts throwing I/O errors, the canonical sequence is: unmount → verifyDisk → repairDisk → verifyVolume per slice → repairVolume per slice. If repair fails, restore from backup and re-format.

bash

sudo diskutil unmountDisk force /dev/disk4
sudo diskutil verifyDisk disk4
sudo diskutil repairDisk disk4
sudo diskutil verifyVolume disk4s2
sudo diskutil repairVolume disk4s2
diskutil mountDisk disk4

Output:

text

Started partition map verification on disk4
Verifying the partition list
Verifying the partition map size
Checking prerequisites
Checking the partition list
Checking the partition map
The partition map appears to be OK.
Finished partition map verification on disk4

Free up disk by purging Time Machine local snapshots

When your boot drive shows "Purgeable" space you can't recover, the culprit is usually local Time Machine snapshots. diskutil lists them; tmutil deletes them.

bash

# List
diskutil apfs listSnapshots / | grep -E "Name:|XID:"

# Delete every local TM snapshot older than today (handled by tmutil)
for s in $(tmutil listlocalsnapshotdates / | tail -n +2); do
  sudo tmutil deletelocalsnapshots "$s"
done

# Confirm
diskutil apfs listSnapshots / | grep -c "Name:"

Output:

text

Name: com.apple.TimeMachine.2026-05-23-093011.local
XID:  812345
Name: com.apple.TimeMachine.2026-05-24-092805.local
XID:  812900
Deleted: 2026-05-23-093011
Deleted: 2026-05-24-092805
0

Sources

Apple — File system formats in Disk Utility — official list of formats Disk Utility / diskutil can create on each macOS release.
Eclectic Light — macOS Tahoe brings a new disk image format (ASIF) — deep-dive on the ASIF format, performance numbers, and the diskutil image create syntax.
Eclectic Light — Local file systems supported by macOS 26 — survey of APFS variants, HFS+, and ExFAT support in Tahoe.
Apple — macOS Tahoe 26 release notes — official changelog for the current macOS release.