- Disk Formats For Mac
- Disk Formats For Macos Computer
- Disk Format For Mac And Windows
- Disk Formats For Macos Download
- How To Format A Mac
Jul 13, 2013 To start, here’s a brief explanation on the different disk formats that you can choose from when formatting an external drive on your Mac and the different pros and cons of each. Choosing the. “Erasing name of disk would erase all data stored in it.” The window would include two inputs: A text box containing the name of the drive, only if you wish to rename it. A drop down consisting of the different formats (FAT32, exFAT, MacOS Extended Journaled) Choose MacOS.
The icon represents an internal hard drive within a generic file icon. | |
Filename extension | |
---|---|
Internet media type | application/x-apple-diskimage |
Uniform Type Identifier (UTI) | com.apple.disk-image |
Developed by | Apple Inc. |
Type of format | Disk image |
Apple Disk Image is a disk image format commonly used by the macOS operating system. When opened, an Apple Disk Image is mounted as a volume within the Macintosh Finder.
An Apple Disk Image can be structured according to one of several proprietary disk image formats, including the Universal Disk Image Format (UDIF) from Mac OS X and the New Disk Image Format (NDIF) from Mac OS 9. Macos for virtualbox for ios development. An Apple disk image file's name usually has '.dmg' as its extension.
Features[edit]
Apple Disk Image files are published with a MIME type of application/x-apple-diskimage.
Different file systems can be contained inside these disk images, and there is also support for creating hybrid optical media images that contain multiple file systems.[1] Some of the file systems supported include Hierarchical File System (HFS), HFS Plus, File Allocation Table (FAT), ISO9660 and Universal Disk Format (UDF).[1][2]
Apple Disk Images can be created using utilities bundled with Mac OS X, specifically Disk Copy in Mac OS X v10.2 and earlier and Disk Utility in Mac OS X v10.3 and later. These utilities can also use Apple disk image files as images for burning CDs and DVDs. Disk image files may also be managed via the command line interface using the hdiutil utility.[3]
In Mac OS X v10.2.3, Apple introduced Compressed Disk Images[4] and Internet-Enabled Disk Images for use with the Apple utility Disk Copy, which was later integrated into Disk Utility in 10.3. The Disk Copy application had the ability to display a multi-lingual software license agreement before mounting a disk image. The image will not be mounted unless the user indicates agreement with the license.[5]
An Apple Disk Image allows secure password protection as well as file compression, and hence serves both security and file distribution functions; such a disk image is most commonly used to distribute software over the Internet.
History[edit]
Apple originally created its disk image formats because the resource fork used by Mac applications could not easily be transferred over mixed networks such as those that make up the Internet. Even as the use of resource forks declined with Mac OS X, disk images remained the standard software distribution format. Disk images allow the distributor to control the Finder's presentation of the window, which is commonly used to instruct the user to copy the application to the correct folder.
A previous version of the format, intended only for floppy disk images, is usually referred to as 'Disk Copy 4.2' format, after the version of the Disk Copy utility that was used to handle these images.[1] A similar format that supported compression of floppy disk images is called DART.[1][6]
New Disk Image Format (NDIF) was the previous default disk image format in Mac OS 9,[1] and disk images with this format generally have a .img (not to be confused with raw .img disk image files) or .smi file extension. Files with the .smi extension are actually applications that mount an embedded disk image, thus a 'Self Mounting Image', intended only for Mac OS 9 and earlier.[7][2]
Universal Disk Image Format (UDIF) is the native disk image format for Mac OS X. Disk images in this format typically have a .dmg extension.[1]
File format[edit]
Apple has not released any documentation on the format, but attempts to reverse engineer parts of the format have been successful. The encrypted layer was reverse engineered in an implementation called VileFault (a spoonerism of FileVault).[8]
Apple disk image files are essentially raw disk images (i.e. contain block data) with some added metadata, optionally with one or two layers applied that provide compression and encryption. In hdiutil these layers are called CUDIFEncoding and CEncryptedEncoding.[1]
UDIF supports ADC (an old proprietary compression format by Apple), zlib, bzip2 (as of Mac OS X v10.4), and LZFSE (as of Mac OS X v10.11)[9] compression internally.
Metadata[edit]
The UDIF metadata is found at the end of the disk image following the data. This trailer can be described using the following C structure.[10] All values are big-endian (PowerPC byte ordering)
The XML plist contains a
blkx
(blocks) key, with information about how the preceeding data fork is allocated. The main data is stored in a base64 block, using tables identified by the magic 'mish'
. This 'mish'
structure contains a table about blocks of data and the position and lengths of each 'chunk' (usually only one chunk, but compression will create more).[10] The data and resource fork information is probably inherited from NDIF.Encryption[edit]
The encryption layer comes in two versions. Version 1 has a trailer at the end of the file, while version 2 (default since OS X 10.5) puts it at the beginning. Whether the encryption is a layer outside of or inside of the
blkx
metadata (UDIF) is unclear from reverse engineered documentation, but judging from the vfcrack
demonstration it's probably outside.[8]Utilities[edit]
There are few options available to extract files or mount the proprietary Apple Disk Image format. Some cross-platform conversion utilities are:
- dmg2img was originally written in Perl; however, the Perl version is no longer maintained, and the project was rewritten in C. Currently, without additional tools, the resulting images may be mounted only under Mac OS X and under Linux (provided hfsplus support has been enabled). UDIF ADC-compressed images (UDCO) have been supported since version 1.5.[11]
- DMGEXtractor is written in Java with GUI, and it supports more advanced features of dmg including AES-128 encrypted images but not UDCO images.[12]
- The Sleuth Kit. Handles the DMG format, HFS+, and APFS.
Most dmg files are unencrypted. Because the dmg metadata is found in the end, a program not understanding dmg files can nevertheless read it as if it was a normal disk image, as long as there is support for the file system inside. Tools with this sort of capacity include:
- Cross-platform: 7-zip (HFS/HFS+), PeaZip (HFS/HFS+).
- Windows: UltraISO, IsoBuster, MacDrive (HFS/HFS+).[13]
- Unix-like: cdrecord and
mount
(e.g.mount -o loop,ro -t hfsplus imagefile.dmg /mnt/mountpoint
).[14][15]
Tools with specific dmg support include:
- Windows:
- Transmac can handle both UDIF dmgs and sparsebundles, as well as HFS/HFS+ and APFS. It is unknown whether it handles encryption.[16] It can be used to create bootable macOS installers under Windows.[17]
- A free Apple DMG Disk Image Viewer also exists, but it is unknown how much what it actually supports.[18].
- Unix-like:
- darling-dmg is a FUSE module enabling easy DMG file mounting on Linux. It supports UDIF and HFS/HFS+.[19]
See also[edit]
References[edit]
![Macos installer disk wipe Macos installer disk wipe](/uploads/1/2/6/5/126585589/143387056.png)
- ^ abcdefg'hdiutil(1) Mac OS X Manual Page'. Archived from the original on 2016-05-14. Retrieved 2016-05-14.
- ^ ab'Mac OS X: Using Disk Copy disk image files'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
- ^
hdiutil(1)
– Darwin and macOS General Commands Manual - ^'Re: Some apps refuse to launch in 10.2.8! (OT, but very important)'. Archived from the original on 2014-01-17.
- ^'Guides'. Apple. Archived from the original on 2009-03-06. Retrieved 2010-10-27.
- ^'DART 1.5.3: Version Change History'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
- ^'Software Downloads: Formats and Common Error Messages'. Archived from the original on 2010-12-24. Retrieved 2009-05-06.
- ^ ab'VileFault'. 2006-12-29. Archived from the original on 2007-01-09. Retrieved 2010-10-27.
- ^Michael Tsai (2015-10-07). 'LZFSE Disk Images in El Capitan'. Archived from the original on 2017-04-09. Retrieved 2017-04-09.
- ^ ab'Demystifying the DMG File Format'. Archived from the original on 2013-03-17.
- ^'dmg2img'. Archived from the original on 29 November 2010. Retrieved 2010-10-27.
- ^'DMGExtractor'. Archived from the original on 2011-01-02. Retrieved 2011-01-03.
- ^MacDrive Features / Boot Camp / System Requirements /. 'MacDrive Home page'. Mediafour. Archived from the original on 4 October 2010. Retrieved 2010-10-27.
- ^'How To Convert DMG To ISO in Windows, Linux & Mac'. Archived from the original on 2010-03-07.
- ^'Convert DMG To ISO using PowerISO'. Archived from the original on 2009-05-02. Retrieved 2009-02-15.
- ^'About TransMac for Windows'. www.acutesystems.com.
- ^'Convert'. www.winytips.com. winytips. Retrieved 5 May 2020.
- ^Olivia Dehaviland (2015-03-03). 'Apple DMG Disk Image Viewer'. DataForensics.org. Archived from the original on 2015-04-02. Retrieved 2015-03-10.
- ^'darling-dmg'. darling-dmg. Retrieved 29 March 2015.
External links[edit]
- Apple Developer Connection A Quick Look at PackageMaker and Installer
- O'Reilly Mac DevCenter Tip 16-5. Create a Disk Image from a Directory in the Terminal
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Apple_Disk_Image&oldid=966546185'
WARNING: Formatting will erase all data on the device. Back up all your data before proceeding.
Instructions below are for 10.11.x (El Capitan) and 10.12.x (Sierra)
1. Double-click on Macintosh HD - or in the Finder menu clickFile > New Finder Window
2. Click the Applications folder - if using a Finder Window Applicationswill be in the left side menu.
3. Click the Utilities folder.
4. Double-click Disk Utility.
5. On the left side of the window are the drives connected to the computer. Select the capacity of the drive respective to the one containing the device you wish to format then click the Erase tab.
Example: If the drive is called 'NO NAME', directly above that, you should see the drive capacity of 'XXXX'. Select this capacity.
6. Verify Volume Format is set to MS-DOS file system or exFAT, Scheme is set to “Master Boot Record” (Do NOT select GUID Partition Map) then click Erase.
2. Click the Applications folder - if using a Finder Window Applicationswill be in the left side menu.
3. Click the Utilities folder.
4. Double-click Disk Utility.
5. On the left side of the window are the drives connected to the computer. Select the capacity of the drive respective to the one containing the device you wish to format then click the Erase tab.
Example: If the drive is called 'NO NAME', directly above that, you should see the drive capacity of 'XXXX'. Select this capacity.
6. Verify Volume Format is set to MS-DOS file system or exFAT, Scheme is set to “Master Boot Record” (Do NOT select GUID Partition Map) then click Erase.
Instructions below are for 10.13.x (High Sierra)
Disk Formats For Mac
1. Open Disk Utility. Please See Answer 20985: How to access Disk Utility macOS
2. In the top menu bar, go to View, and choose Show All Devices
2. In the top menu bar, go to View, and choose Show All Devices
3. Select the upper level of the drive you would like to format and click the Erase button
4. Choose how you would like to format the drive
Disk Formats For Macos Computer
- Enter a Name for your drive
- Choose exFAT or MS-DOS (FAT) for the format
- Choose Master Boot Record for the Scheme
- Click Erase
Disk Format For Mac And Windows
5. When finished, the drive will be formatted and repartitioned successfully. Click the Done button
Disk Formats For Macos Download
NOTE: exFAT is used on SDXC card (64GB and higher).
NOTE: exFAT can be used on flash drives or memory cards to transfer files larger than 4GB.
NOTE: MacOS 10.6.2 or higher is required for exFAT file system. Some older operating systems must have a patch installed before they can use the exFAT file system.
How To Format A Mac
NOTE: If the above steps do NOT resolve the problem or if the lock switch is missing or broken, please back up your data and request a replacement using our online web form.
![Disk Disk](/uploads/1/2/6/5/126585589/865866506.webp)
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