- What Is A Disk Image Backup
- What Is A Disk Image File On A Mac
- What Is A Disk Image In Idrive
- What Is A Disk Image Windows
- What Does Disk Image Mean
A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is a file that's the exact copy of a disk volume or of an entire physical disk drive. This copy retains all the properties of its source: files, folders, properties and the disk's name. Disk images are a handy way of storing backup copies of your disks. For instance, you might have some Audio CDs which you play on a regular basis. Nov 30, 2020 In a nutshell, it refers to the process of copying all the contents including Windows boot records, files, settings, and programs on your hard drive to another disk. Moreover, an exact same copy of the source disk is created, no compression. Namely, the contents of the destination disk are identically the same as the source disk. Mar 10, 2017 Differential backups keep a record of any changes made since the full image was created, so restoring a system requires the full image and the latest differential image.
Disk Utility User Guide
You can use Disk Utility to create a disk image, which is a file that contains other files and folders.
Note: You can burn information to a CD or DVD using the Burn command in the Finder. See Burn CDs and DVDs.
What Is A Disk Image Backup
Create a blank disk image for storage
You can create an empty disk image, add data to it, then use it to create disks, CDs, or DVDs.
What Is A Disk Image File On A Mac
In the Disk Utility app on your Mac, choose File > New Image > Blank Image.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
In the Name field, enter the name for the disk image.
This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.
In the Size field, enter a size for the disk image.
Click the Format pop-up menu, then choose the format for the disk:
If the disk image will be used with a Mac that has a solid state drive (SSD) and uses macOS 10.13 or later, choose APFS or APFS (Case-sensitive).
If the disk image will be used with a Mac with macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled).
If the disk image will be used with a Mac or Windows computer and is 32 GB or less, choose MS-DOS (FAT); if it's over 32 GB, choose ExFAT.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click the Partitions pop-up menu, then choose a partition layout.
Click the Image Format pop-up menu, then choose an option:
Sparse bundle disk image: Same as a sparse disk image (below), but the directory data for the image is stored differently. Uses the .sparsebundle file extension.
Sparse disk image: Creates an expandable file that shrinks and grows as needed. No additional space is used. Uses the .sparseimage file extension.
Read/write disk image: Allows you to add files to the disk image after it's created. Uses the .dmg file extension.
DVD/CD master: Changes the size of the image to 177 MB (CD 8 cm). Uses the .cdr file extension.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
In the Finder, copy your files to the mounted disk image, then eject it.
Restore the disk image to a disk.
For more information about disk image types, see the manual (man) page for hdiutil.
Create a disk image from a disk or connected device
You can create a disk image that includes the data and free space on a physical disk or connected device, such as a USB device. For example, if a USB device or volume is 80 GB with 10 GB of data, the disk image will be 80 GB in size and include data and free space. You can then restore that disk image to another volume.
In the Disk Utility app on your Mac, select a disk, volume, or connected device in the sidebar.
Choose File > New Image, then choose 'Image from [device name].'
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
Click the Format pop-up menu, then choose an option:
Read-only: The disk image can't be written to, and is quicker to create and open.
Compressed: Compresses data, so the disk image is smaller than the original data. The disk image is read-only.
Read/write: Allows you to add files to the disk image after it's created.
DVD/CD master: Can be used with third-party apps. It includes a copy of all sectors of the disk image, whether they're used or not. When you use a master disk image to create other DVDs or CDs, all data is copied exactly.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
Important: Don't create a disk image of a disk that you believe to be failing or that contains corrupted information. The disk image may not serve as a reliable backup.
For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.
Create a disk image from a folder or connected device
You can create a disk image that contains the contents of a folder or connected device, such as a USB device. This method doesn't copy a device's free space to the disk image. For example, if a USB device or volume is 80 GB with 10 GB of data, the disk image will be 10 GB in size and include only data, not free space. You can then restore that disk image to another volume.
In the Disk Utility app on your Mac, choose File > New Image, then choose Image from Folder.
Select the folder or connected device in the dialog that appears, then click Open.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click the Image Format pop-up menu, then choose an option:
Read-only: The disk image can't be written to, and is quicker to create and open.
Compressed: Compresses data, so the disk image is smaller than the original data. The disk image is read-only.
Read/write: Allows you to add files to the disk image after it's created.
DVD/CD master: Can be used with third-party apps. It includes a copy of all sectors of the disk image, whether they're used or not. When you use a master disk image to create other DVDs or CDs, all data is copied exactly.
Hybrid image (HFS+/ISO/UDF): This disk image is a combination of disk image formats and can be used with different file system standards, such as HFS, ISO, and UDF.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
Logic pro trial. For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.
Create a secure disk image
If you have confidential documents that you don't want others to see without your permission, you can put them in an encrypted disk image.
Note: If you want to protect the contents of the system disk, turn on FileVault using the FileVault pane of Security & Privacy Preferences.
In the Disk Utility app on your Mac, choose File > New Image > Blank Image.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
In the Name field, enter the name for the disk image.
This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.
In the Size field, enter a size for the disk image.
Click the Format pop-up menu, then choose a format:
If you're using the encrypted disk image with a Mac computer using macOS 10.13 or later, choose APFS or APFS (Case-sensitive).
If you're using the encrypted disk image with a Mac computer using macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled).
Click the Encryption pop-up menu, then choose an encryption option.
Enter and re-enter a password to unlock the disk image, then click Choose.
WARNING: If you forget this password, you won't be able to open the disk image and view any of the files.
Use the default settings for the rest of the options:
Click the Partitions pop-up menu, then choose Single partition - GUID Partition Map.
Click the Image Format pop-up menu, then choose 'read/write' disk image.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
In the Finder , copy the documents you want to protect to the disk image.
If you want to erase the original documents so they can't be recovered, drag them to the Trash, then choose Finder > Empty Trash.
When you're finished using the documents on the secure disk image, be sure to eject the disk image. As long as it's available on your desktop, anyone with access to your computer can use the documents on it.
To access the data in a disk image, double-click it. It appears on your desktop, and you can add, remove, and edit files on it just as you would with a disk.
User's Guides Active@ Disk Image
What Is A Disk Image In Idrive
About Disk Image Types
What Is A Disk Image Windows
Disk image software Active@ Disk Image supports backup type and raw type disk images.
Backup Disk Image is the default type and should be used in most cases. When Raw Disk Image type is not mentioned explicitly in this guide, we are referring to the Backup Disk Image. Another file format supported is ISO image. ISO images are used to store a copy of CD/DVD/Blue-ray disc in a file and stand apart from actual disk images.
Backup Disk Images
A Backup Disk Image contains only data found in used sectors of a hard drive. This is done in order to reduce the size of the disk image file and to reduce the time it takes to create the disk image.
One Backup Disk Image archive can hold data from several partitions from one or more disks. When you select a partition to be backed up, all current data will be saved into the disk image archive.
Data that is recognized as deleted files and unused partition areas are not recorded into the image. Windows pagefiles and hibernation file data are also excluded from a Backup Disk Image because they contain temporary information which is useless to keep and restore.
Active@ Disk Image can make a backup of any file system. If a partition selected for backup is formatted with a file system that is not supported by Disk Image natively (i.e. FAT or NTFS are supported), a sector-by-sector (raw) backup will be performed.
Keep in mind that this mode is different from raw disk images described below. The image of partition of unknown file system will be placed into .ADI file; the major difference from NTFS and FAT partitions is that it will contain all sectors of the partition - used and free.
Raw Disk Images
A Raw Disk Image contains an exact, sector-by-sector copy of a single partition or disk. A Raw Disk Image of a disk or a partition is a larger file than a Backup Disk Image of the same disk or partition and it takes a longer time to create.
A Raw Disk Image archive can hold data from only one disk; either a whole disk or one partition from a single disk. It cannot contain more than one selected partition. To make a Raw Disk Image of several partitions on various disks, you may create a separate Raw Disk Image for each partition.
ISO images
ISO image is a standard format which contains an exact, sector-by-sector copy of an optical media as CD/DVD/Blue-ray disc. It is used automatically when a CD/DVD/Blue-ray disc is selected for backup. ISO image can be burned back to the optical media.
When to use Raw Disk Images
In normal conditions, you will likely use Backup Disk Images. A Backup Disk Image has the following advantages over a Raw Disk Image:
- A Backup Disk Image file is smaller than a Raw Disk Image file (while containing all your valuable and usable data).
- It takes less time to create a Backup Disk Image than it takes to create a Raw Disk Image.
- The Backup Disk Image process has advanced features like storing several partitions in one image, password protection and variable compression options.
Raw Disk Images are more helpful in a data recovery scenario. Here are some reasons why a Raw Disk Image is superior for data recovery:
- Data recovery technologies are based on searching the unused space on a partition for traces of deleted, lost or damaged files and folders. So-called 'unused space' on a partition is not recognized by the file system and is not saved to a Backup Disk Image. However, this space might contain valuable data information and it is saved to a Raw Disk Image.
- The uncompressed Raw Disk Image file contains a sequence of sectors that is unchanged from the original. There are no headers or other application specific identifiers added. As a result, the Raw Disk Image can be viewed by any data rescue software as a mirror of your drive. If the integrity of the data on your live disk is questionable, you may want to experiment with the data on the partition image instead.
- If file size is an issue, a compressed Raw Disk Image may be used. Active@ Undelete is an example of data recovery software which can work with both compressed and uncompressed Raw Disk Images.
- Raw Disk Image have no regard for the file system type. During the Raw Disk Image recording process, all sectors are backed up. An image of any partition can be created and restored.
- If you want the data from a file to be restored from the disk image to the same exact location as they were before, then use a Raw Disk Image. A Backup Disk Image saves all current data but restores files to different sectors, allowing the partition to shrink or grow, depending on the size of the replaced file. In a regular situation, you should not be concerned about partition size. If the partition size is important, however, a Raw Disk Image is the solution.
Note: You can burn information to a CD or DVD using the Burn command in the Finder. See Burn CDs and DVDs.
What Is A Disk Image Backup
Create a blank disk image for storage
You can create an empty disk image, add data to it, then use it to create disks, CDs, or DVDs.
What Is A Disk Image File On A Mac
In the Disk Utility app on your Mac, choose File > New Image > Blank Image.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
In the Name field, enter the name for the disk image.
This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.
In the Size field, enter a size for the disk image.
Click the Format pop-up menu, then choose the format for the disk:
If the disk image will be used with a Mac that has a solid state drive (SSD) and uses macOS 10.13 or later, choose APFS or APFS (Case-sensitive).
If the disk image will be used with a Mac with macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled).
If the disk image will be used with a Mac or Windows computer and is 32 GB or less, choose MS-DOS (FAT); if it's over 32 GB, choose ExFAT.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click the Partitions pop-up menu, then choose a partition layout.
Click the Image Format pop-up menu, then choose an option:
Sparse bundle disk image: Same as a sparse disk image (below), but the directory data for the image is stored differently. Uses the .sparsebundle file extension.
Sparse disk image: Creates an expandable file that shrinks and grows as needed. No additional space is used. Uses the .sparseimage file extension.
Read/write disk image: Allows you to add files to the disk image after it's created. Uses the .dmg file extension.
DVD/CD master: Changes the size of the image to 177 MB (CD 8 cm). Uses the .cdr file extension.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
In the Finder, copy your files to the mounted disk image, then eject it.
Restore the disk image to a disk.
For more information about disk image types, see the manual (man) page for hdiutil.
Create a disk image from a disk or connected device
You can create a disk image that includes the data and free space on a physical disk or connected device, such as a USB device. For example, if a USB device or volume is 80 GB with 10 GB of data, the disk image will be 80 GB in size and include data and free space. You can then restore that disk image to another volume.
In the Disk Utility app on your Mac, select a disk, volume, or connected device in the sidebar.
Choose File > New Image, then choose 'Image from [device name].'
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
Click the Format pop-up menu, then choose an option:
Read-only: The disk image can't be written to, and is quicker to create and open.
Compressed: Compresses data, so the disk image is smaller than the original data. The disk image is read-only.
Read/write: Allows you to add files to the disk image after it's created.
DVD/CD master: Can be used with third-party apps. It includes a copy of all sectors of the disk image, whether they're used or not. When you use a master disk image to create other DVDs or CDs, all data is copied exactly.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
Important: Don't create a disk image of a disk that you believe to be failing or that contains corrupted information. The disk image may not serve as a reliable backup.
For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.
Create a disk image from a folder or connected device
You can create a disk image that contains the contents of a folder or connected device, such as a USB device. This method doesn't copy a device's free space to the disk image. For example, if a USB device or volume is 80 GB with 10 GB of data, the disk image will be 10 GB in size and include only data, not free space. You can then restore that disk image to another volume.
In the Disk Utility app on your Mac, choose File > New Image, then choose Image from Folder.
Select the folder or connected device in the dialog that appears, then click Open.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click the Image Format pop-up menu, then choose an option:
Read-only: The disk image can't be written to, and is quicker to create and open.
Compressed: Compresses data, so the disk image is smaller than the original data. The disk image is read-only.
Read/write: Allows you to add files to the disk image after it's created.
DVD/CD master: Can be used with third-party apps. It includes a copy of all sectors of the disk image, whether they're used or not. When you use a master disk image to create other DVDs or CDs, all data is copied exactly.
Hybrid image (HFS+/ISO/UDF): This disk image is a combination of disk image formats and can be used with different file system standards, such as HFS, ISO, and UDF.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
Logic pro trial. For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.
Create a secure disk image
If you have confidential documents that you don't want others to see without your permission, you can put them in an encrypted disk image.
Note: If you want to protect the contents of the system disk, turn on FileVault using the FileVault pane of Security & Privacy Preferences.
In the Disk Utility app on your Mac, choose File > New Image > Blank Image.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
In the Name field, enter the name for the disk image.
This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.
In the Size field, enter a size for the disk image.
Click the Format pop-up menu, then choose a format:
If you're using the encrypted disk image with a Mac computer using macOS 10.13 or later, choose APFS or APFS (Case-sensitive).
If you're using the encrypted disk image with a Mac computer using macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled).
Click the Encryption pop-up menu, then choose an encryption option.
Enter and re-enter a password to unlock the disk image, then click Choose.
WARNING: If you forget this password, you won't be able to open the disk image and view any of the files.
Use the default settings for the rest of the options:
Click the Partitions pop-up menu, then choose Single partition - GUID Partition Map.
Click the Image Format pop-up menu, then choose 'read/write' disk image.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
In the Finder , copy the documents you want to protect to the disk image.
If you want to erase the original documents so they can't be recovered, drag them to the Trash, then choose Finder > Empty Trash.
When you're finished using the documents on the secure disk image, be sure to eject the disk image. As long as it's available on your desktop, anyone with access to your computer can use the documents on it.
To access the data in a disk image, double-click it. It appears on your desktop, and you can add, remove, and edit files on it just as you would with a disk.
User's Guides Active@ Disk Image
What Is A Disk Image In Idrive
About Disk Image Types
What Is A Disk Image Windows
Disk image software Active@ Disk Image supports backup type and raw type disk images.
Backup Disk Image is the default type and should be used in most cases. When Raw Disk Image type is not mentioned explicitly in this guide, we are referring to the Backup Disk Image. Another file format supported is ISO image. ISO images are used to store a copy of CD/DVD/Blue-ray disc in a file and stand apart from actual disk images.
Backup Disk Images
A Backup Disk Image contains only data found in used sectors of a hard drive. This is done in order to reduce the size of the disk image file and to reduce the time it takes to create the disk image.
One Backup Disk Image archive can hold data from several partitions from one or more disks. When you select a partition to be backed up, all current data will be saved into the disk image archive.
Data that is recognized as deleted files and unused partition areas are not recorded into the image. Windows pagefiles and hibernation file data are also excluded from a Backup Disk Image because they contain temporary information which is useless to keep and restore.
Active@ Disk Image can make a backup of any file system. If a partition selected for backup is formatted with a file system that is not supported by Disk Image natively (i.e. FAT or NTFS are supported), a sector-by-sector (raw) backup will be performed.
Keep in mind that this mode is different from raw disk images described below. The image of partition of unknown file system will be placed into .ADI file; the major difference from NTFS and FAT partitions is that it will contain all sectors of the partition - used and free.
Raw Disk Images
A Raw Disk Image contains an exact, sector-by-sector copy of a single partition or disk. A Raw Disk Image of a disk or a partition is a larger file than a Backup Disk Image of the same disk or partition and it takes a longer time to create.
A Raw Disk Image archive can hold data from only one disk; either a whole disk or one partition from a single disk. It cannot contain more than one selected partition. To make a Raw Disk Image of several partitions on various disks, you may create a separate Raw Disk Image for each partition.
ISO images
ISO image is a standard format which contains an exact, sector-by-sector copy of an optical media as CD/DVD/Blue-ray disc. It is used automatically when a CD/DVD/Blue-ray disc is selected for backup. ISO image can be burned back to the optical media.
When to use Raw Disk Images
In normal conditions, you will likely use Backup Disk Images. A Backup Disk Image has the following advantages over a Raw Disk Image:
- A Backup Disk Image file is smaller than a Raw Disk Image file (while containing all your valuable and usable data).
- It takes less time to create a Backup Disk Image than it takes to create a Raw Disk Image.
- The Backup Disk Image process has advanced features like storing several partitions in one image, password protection and variable compression options.
Raw Disk Images are more helpful in a data recovery scenario. Here are some reasons why a Raw Disk Image is superior for data recovery:
- Data recovery technologies are based on searching the unused space on a partition for traces of deleted, lost or damaged files and folders. So-called 'unused space' on a partition is not recognized by the file system and is not saved to a Backup Disk Image. However, this space might contain valuable data information and it is saved to a Raw Disk Image.
- The uncompressed Raw Disk Image file contains a sequence of sectors that is unchanged from the original. There are no headers or other application specific identifiers added. As a result, the Raw Disk Image can be viewed by any data rescue software as a mirror of your drive. If the integrity of the data on your live disk is questionable, you may want to experiment with the data on the partition image instead.
- If file size is an issue, a compressed Raw Disk Image may be used. Active@ Undelete is an example of data recovery software which can work with both compressed and uncompressed Raw Disk Images.
- Raw Disk Image have no regard for the file system type. During the Raw Disk Image recording process, all sectors are backed up. An image of any partition can be created and restored.
- If you want the data from a file to be restored from the disk image to the same exact location as they were before, then use a Raw Disk Image. A Backup Disk Image saves all current data but restores files to different sectors, allowing the partition to shrink or grow, depending on the size of the replaced file. In a regular situation, you should not be concerned about partition size. If the partition size is important, however, a Raw Disk Image is the solution.
About disk image file names
- Backup Disk Images
Backup Disk Images have the file extension .ADI.
All data is stored in one file or in a sequential series of numbered files. When the disk image is split into several files, additional file names are created by adding sequential numbers to the original name.
Here is an example: If you save a Backup Disk Image with the name MyImage, the application creates a file named MyImage.adi at the specified location for the first image file. If you have configured the operation to split the image after a fixed file size, or if the image is split automatically, the next file name is MyImage1.adi. The next file name after that is MyImage2.adi, and so on.
- Raw Disk Images
Raw Disk Images have the file extension .DIM.
What Does Disk Image Mean
A Raw Disk Image consists of two files: a configuration file and data file. The configuration file describes the disk or partition geometry and keeps the image description. This file has the .DIM extension. When verifying or exploring a Raw Disk Image, select this file.
The raw image data files have numerical extensions starting from .001 added to the whole image name.
Here is an example: If you save a Raw Disk Image with the name MyImage, the application creates a file named MyImage.dim. This is the configuration file. Data is stored in a file named MyImage.dim.001. If more than one file is created, the next file is named MyImage.dim.002, and so on.
- ISO images
ISO images have the file extension .ISO. One .ISO file contains image of one optical disc, thus for every optical drive selected there will be a separate .ISO file created. Backup folder
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