Backup And Restore Core Storage Configuration With HDM For Mac

Overview

Unlike traditional configurations, Apple Core Storage requires a different backup approach. In this article you will learn the basics about the Apple Core Storage, FileVault and Fusion Drive technologies, while several step-by-step scenarios will help you correctly back up and restore any of these configurations with Paragon Hard Disk Manager for Mac.

What is Apple Core Storage?

Core Storage is a logical volume format introduced by Apple that serves the basis for FileVault (Full Disk Encryption) and Fusion Drive technologies. In short, the Core Storage is a layer between the disk partition scheme and the file system. It works by including one or several physical volumes (PV) into a logical volume group (LVG), where one or more logical volumes (LV) can be resided.

Normally, a PV is a real storage device like an SSD (Solid State Drive) or a traditional HDD (Hard Disk Drive), but it can be a disk image or even a RAID set. A PV is always a partition on a GPT (GUID Partition Table) disk with a specific GUID (53746F72-6167-11AA-AA11-00306543ECAC). It is important to note that data from physical volumes cannot be retrieved directly, because they don’t have a standard file system.

Though a Logical Volume Group may contain one or several logical volumes, in standard configurations it is one volume with a total capacity of all physical volumes. It’s an LV that hosts a standard file system (such as HFS+), where all data is organized in a traditional way, so it can be easily accessed and read.

About FileVault

First appeared in OS X Lion, the FileVault enables to dynamically encrypt on-disk partitions. Initially encrypting all contents of the target physical volume, it utilizes the Core Storage to grant access to requested data on a logical volume. This saves from the need of decrypting all contents at system login after authentication, which is good for security.

A typical FileVault configuration:

/dev/disk0 – a physical storage device with several volumes.
/dev/disk0s3 – a physical volume on /dev/disk0, which contents are encrypted and it is included into Core Storage LVG.
/dev/disk1 – a logical volume on the LVG that is an entry point to decrypted contents of /dev/disk0s3.

About Fusion Drive

For years people have been using several storage devices in their systems, choosing the fastest disk for OS and critical applications, while storing media files and other data on something slower, but much cheaper per gigabyte. Until recently, there was no mechanism for automating the process of arranging files between disks, so it was up to the user to decide. Obviously, this type of activity required specific knowledge and time, few could afford. With the Fusion Drive technology Apple offered a solid solution to this problem.

A typical Fusion Drive configuration:

/dev/disk0 – a physical hard disk drive included into Core Storage LVG.
/dev/disk1 – a physical solid state drive included into Core Storage LVG.
/dev/disk2 – a logical volume on the LVG that is an entry point to contents of both physical storage devices.

A special filter-driver operating in the background ensures that boot-critical OS files and the most frequently used data are stored on the fastest device in the pool (SSD in our example), while all the rest on the HDD. Furthermore, it never allows any less than 4GB of free space on the SSD.

A fusion drive configuration is displayed as one mounted drive in the system, which capacity is a total of the SSD and HDD, while the physical storage devices that make up the logical volume group are hidden for the user.

Paragon Hard Disk Manager for Mac (HDM for Mac) for instance doesn’t hide anything, providing detailed information on all physical and logical volumes mounted in the system.

Backup Scenarios

Backing up a Core Storage Configuration With One Physical Disk (Mac Book Layout)

As we already know, a Core Storage configuration is organized in such a way that it is logical volumes (LV) that open access to on-disk contents for the user and applications, while physical volumes (PV) that make it up don’t even have a standard file system. Thus if you’d like to back up this type of configurations, you need to exclude PVs from the process, as they are of no importance.

As the first example, let’s see how to correctly back up a typical Mac Book with one internal physical storage device configured as Core Storage with HDM for Mac.

Start the Backup Wizard by selecting Backup and Restore in the upper area, then clicking Create new Archive.
The program displays all physical and logical volumes mounted in the system. Please make sure you select service partitions (Boot OS X, EFI, Recovery) and a Core Storage Logical Volume, while removing a Core Storage Physical Volume (a gray one) from the process.
Click the arrow icon to set a backup location. HDM for Mac enables to place backup images to a local volume, external storage, or a network share. We highly recommend you to use either an externally connected disk (USB, ThunderBolt, FireWire) or a network share. Please take into account values of the parameters “Available space” and “Estimated backup size” – if the backup size exceeds the available storage space, the operation won’t proceed. Don’t forget to give a catchy file name for the backup image and add description if necessary.
That’s all. Click Backup to initiate the operation, which may take quite a while (depends on the amount of data to process).

Backing up a Fusion Drive Configuration (SSD + HDD)

As in the previous scenario the main rule is to exclude Core Storage Physical Volumes from backup. For Fusion Drives there should be no less than two PVs.

Start the Backup Wizard by selecting Backup and Restore in the upper area, then clicking Create new Archive.
Please make sure you select service partitions (Boot OS X, EFI, Recovery) and a Core Storage Logical Volume, while removing Core Storage Physical Volumes from the process. In our case it’s an SSD and a traditional spinning platter HDD.
Click the arrow icon to set a backup location. HDM for Mac enables to place backup images to a local volume, external storage, or a network share. We highly recommend you to use either an externally connected disk (USB, ThunderBolt, FireWire) or a network share. Please take into account values of the parameters “Available space” and “Estimated backup size” – if the backup size exceeds the available storage space, the operation won’t proceed. Don’t forget to give a catchy file name for the backup image and add description if necessary.
That’s all. Click Backup to initiate the operation, which may take quite a while (depends on the amount of data to process).
Once the backup image is created, you can see its contents. Please note that there are two blocks of free space in place of Core Storage Physical Volumes.

Restore Scenarios

Preparing Recovery Media

Recovery Media can help you boot your Mac into Recovery Environment to get access to your hard disk for maintenance or recovery purposes. It includes a standard set of utilities (terminal, reinstall os x tool, etc.) and the Hard Disk Manager application. HDM for Mac includes a special wizard that will guide you through the process of creating the media on a flash stick or external disk.

Start the Create Recovery Media Wizard by selecting from the main menu: Wizards > Create Recovery Media.
Choose a flash stick or external disk from the list of available storage devices. Please not that all data on this device will be deleted.
Confirm erasing the disk.
The entire process takes a couple of minutes.
Once completed, you will be prompted to restart your Mac from the just created media.If you decide not to do it right now, click Don’t restart.
To start up the computer from the boot media later you will need to hold the Option (alt) key during the system restart until the Startup Manager appears, then select the “HDM Recovery” as boot source. Alternatively, you can use the Startup Disk System Preferences.

Restoring to Original Location

It’s a basic restore scenario that can help to get the system back on track when accidentally deleting several or all files from the system partition. Please note that you can use it when the partition structure on the source disk hasn’t been changed much.

Restart your Mac from the Recovery Media by holding the Option (alt) key during the system restart until the Startup Manager appears, then selecting the “HDM Recovery” as boot source.
Choose a backup image you’d like to restore, then click Restore Archive. If you’ve got a backup image(s) located on a network share, please make sure this share is mapped. Otherwise the image won’t be available to work with.
Select Restore to original location.
The wizard displays contents of the specified backup image. Choose all backup objects for restore.
Check the resulted disk layout. As you can see, there will be recovered about 10GB of data. Click Restore to initiate the operation, which may take quite a while (depends on the amount of data to process).
Once completed, restart your Mac from the internal storage device.

Restoring a Core Storage Logical Volume Group as a Physical Volume

HDM for Mac includes an option to restore a Core Storage Logical Volume as an ordinary GPT physical volume. This scenario can help to restore data from a backup image when the partition structure on the source disk has been through major changes, e.g. after deletion of the Core Storage Logical Group or when you need to restore to a different (non-original) disk.

The restore process consists of two phases.

First, you need to recover all data from a backup image, except for a Core Storage Logical Group and Volume:

Restart your Mac from the Recovery Media by holding the Option (alt) key during the system restart until the Startup Manager appears, then selecting the “HDM Recovery” as boot source.
Choose a backup image you’d like to restore, then click Restore Archive.
Select Selective restore.
The wizard displays contents of the specified backup image. Choose only physical backup objects for restore, while excluding all the rest.
Select a target disk of enough capacity for restore.
Check the resulted disk layout. Make sure the “Restore as is” option is selected.
Confirm the operation, then click Restore to start.

Second, you need to recover a Core Storage Logical Volume as a single GPT physical volume:

Choose a backup image you’d like to restore, then click Restore Archive.
Select Restore single partition.
The wizard displays contents of the specified backup image. This time you need to choose only logical backup objects for restore, while excluding all the rest.
Select a free block on the target disk you specified during the first phase for restore.
Use the sliders to set a size for the restored partition.
Check the resulted disk layout. Click Restore to initiate the operation, which will take quite a while as about 10GB of data is going to be copied.

Restoring a Fusion Drive (or Any Other Core Storage Logical Volume Group) to New (Empty) Disks

This scenario can help when all data from SSD and HDD included into a Fusion Drive configuration has been lost, leaving both storage devices unformatted.

To get everything back on track, it’s first required to organize a new Core Storage Logical Volume Group and then restore backup contents to it.

Restart your Mac from the Recovery Media by holding the Option (alt) key during the system restart until the Startup Manager appears, then selecting Utilities > Terminal.
Create a Core Storage Logical Volume Group using the “diskutil”:Syntax: diskutil coreStorage create LOGICAL_VOL_GROUP_NAME DRIVE_1 DRIVE_2

*The “diskutil coreStorage create” command accepts any number of disks or HFS+ partitions (for example: diskutil cs create NewLVG /dev/disk0 /dev/disk1s2 /dev/disk2s2). During the process partitions will be converted to the “Apple Core Storage” GPT type, while disks – formatted using the GPT partition scheme.*
Create a new Logical Volume on the LVG.Syntax: diskutil coreStorage createVolume lvgUUID type name size
As a result of these actions, a new “Fusion Drive” should appear in the system. Now everything’s ready for restore.
Close the terminal and start Hard Disk Manager for Mac.
Choose a backup image you’d like to restore, then click Restore Archive.
Select Restore single partition.
Select the Core Storage Logical Volume (“Macintosh HD” in our case). If you’re not sure, choose an HFS+ volume that is a total capacity of disks included in your Fusion Drive configuration.
Select the previously created Logical Volume as a target disk.
Check the resulted disk layout. Click Restore to initiate the operation.
Once completed, close HDM for Mac, then go to the “Startup Disk” menu. Select “Macintosh HD” on the internal hard drive as Startup Disk, then confirm reboot