IMac 27 Fusion Drive restore from SSD

fusion-driveimacmacbook prossd

How can I restore an image (dmg) of my MacBook's 512 GB SSD (APFS encrypted) onto a 1 TB Fusion Drive using Disk Utility?

I am a bit confused with the Fusion Drive. Can I make it pure HDD and just do an old-school Disk Utility restore?

Currently after messing a bit with it I am facing "problems were found with the partition map which might prevent booting" when running first aid on HDD.

The state of the iMacs disks is like that:

UPDATE:

get to the point where I have OS X installed back and following setup:

Best Answer

Currently you can't restore an APFS container to a "fusioned" Fusion Drive.

A Fusion Drive consists at least of two physical devices - one of them should be an SSD or you wouldn't benefit from its speed. The other one is an HDD to benefit from the price-to-size ratio.

A "fusioned" Fusion Drive combines one partition of the SSD drive and one partition of the HDD with the help of a logical volume manger (CoreStorage) to a contiguous logical volume group which can be divided into several logical volumes. Usually it's only one though.

Example:

3.1 TB Fusion Drive:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         121.0 GB   disk0s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *3.0 TB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:          Apple_CoreStorage                         3.0 TB     disk1s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3

Disk0 is an SSD, disk1 is an HDD. Each disk contains three partitions: diskXs1, diskXs2 and diskXs3. By default diskXs1 is an ~200 MB or ~300 MB EFI partition (depends on the block size). DiskXs3 is an Apple_Boot partition with various sizes. Usually the 3rd partition of the HDD is the recovery partition with 650 MB though.

Both diskXs2s are managed by the logical volume manager:

+-- Logical Volume Group A783F70E-04C1-49C1-80F8-D6E9B43DDC71
    =========================================================
    Name:         Macintosh HD
    Status:       Online
    Size:         3120722075648 B (3.1 TB)
    Free Space:   114688 B (114.7 KB)
    |
    +-< Physical Volume 00F83435-0AD3-4E21-B884-6B26D1664028
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     120988852224 B (121.0 GB)
    |
    +-< Physical Volume CE0BE70D-9502-4C6E-A0F9-994F887A7BC1
    |   ----------------------------------------------------
    |   Index:    1
    |   Disk:     disk1s2
    |   Status:   Online
    |   Size:     2999733223424 B (3.0 TB)
    |
    +-> Logical Volume Family 63FFE3F6-E787-48A6-923A-2A62CDBB948C
        ----------------------------------------------------------
        Encryption Status:       Unlocked
        Encryption Type:         None
        Conversion Status:       NoConversion
        Conversion Direction:    -none-
        Has Encrypted Extents:   No
        Fully Secure:            No
        Passphrase Required:     No
        |
        +-> Logical Volume 9A7B21AA-F9FE-4E65-8C7E-ED2A73744C15
            ---------------------------------------------------
            Disk:                  disk2
            Status:                Online
            Size (Total):          3106191572992 B (3.1 TB)
            Conversion Progress:   -none-
            Revertible:            No
            LV Name:               Macintosh HD
            Volume Name:           Macintosh HD
            Content Hint:          Apple_HFS

Disk0s2 and disk1s2 are united to one large (logical) volume disk2 with the name Macintosh HD and HFS+ formatted.

A pretty undocumented algorithm/process allocates system files, app files and user files often accessed to the SSD part of the logical volume to increase read/write speed.

Your Fusion Drive is "defusioned". It neither contains a Logical Volume Group nor Logical Volumes. Finally they are two simple disks only. Their contents (i.e. partitions) are a mess. One is a giant OS X Base System (which usually is the label of a disk image containing a recovery system with a size of ~1.2-2.0 GB). The SSD contains a defunct APFS partition.

APFS currently doesn't support the combination of two partitions into one superior container/volume properly. Creating an APFS Fusion Drive isn't possible yet.

Though possible APFS on HDDs isn't really recommended.

If you insist on restoring the MB SSD to the HDD I recommend the following:

Format the HDD and install macOS High Sierra
Open Migration Assistant and try to migrate the content of the SSD disk image to the HDD

If you want to restore the image one-to-one use the following steps which depend on how you created the image.

You can either image the container or your mounted main macOS boot volume.

[ enter image description here]2]

If you have imaged the main macOS boot volume only, most APFS volumes (i.e. Preboot, Recovery and VM) won't be added to the image file and they will be missing in the destination container. A restore will finish successfully; the APFS system volume will probably be bootable. To get full functionality you have to reinstall macOS High Sierra.

If you have imaged the whole container, all APFS volumes (including Preboot, Recovery and VM) will be restored.

If your source volume was encrypted and you didn't image the whole container, I doubt that you will successfully restore the image and boot to the result - it's worth a try though. I haven't tested this variant.

In either case you have to "Scan to Restore" the image which requires free space of a similar size as the original image on the same volume!

This can be done in the GUI (Disk Utility) with "Images -> Scan Image for Restore..."

To restore the image, partition the destination drive (your HDD - your SSD is much too small to host the content of the 512 GB SSD) to one APFS container with Disk Utility.

Get the partition details: diskutil list.

Then open Terminal and restore the image (assuming the destination partition is disk0s2):

sudo asr restore -s /path/to/image.dmg -t /dev/disk0s2 --erase

Reboot to the restored main macOS volume.

As mentioned previously reinstall the latest macOS High Sierra version if you didn't image the whole container in the first place.

Related Solutions

Messed up 1TB Fusion Drive Partitions (on iMac 5K)

To expand your CoreStorage Logical Volume Macintosh HD you have to delete the blocking NO NAME EFI partition (disk1s5). The two unnamed parts (138.62 GB and 99.9 GB) are no partitions but unallocated disk space.

To remove the second EFI partition (and expand Macintosh HD) you have to boot to Internet Recovery Mode or an OS X system on an external device.

Preparation:

Backup your data.
Detach any external drive (especially your external Time Machine backup drive).
Restart to Internet Recovery Mode by pressing alt cmd R at startup.
The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot to a recovery netboot image which usually is loaded from an Apple/Akamai server.

I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

Alternatively you may start from a bootable installer thumb drive (Mavericks, Yosemite or El Capitan) or a thumb drive/external disk containing a full system (Mavericks, Yosemite or El Capitan). If you boot from a full system on an external volume and login as a user with admin permissions (which is required) you have to prepend sudo for the gpt command below.

Remove the second EFI partition and modify CoreStorage stack:

Open in the menubar Utilities/Terminal

First you should get an overview of your disks and the partition layout:

Enter diskutil list and gpt -r show /dev/disk1 (assuming disk1 is your HDD)

To resize the CoreStorage volume you have to delete any blocking partition first (the Recovery HD doesn't count because it usually will be moved with the resizeStack command).

First you have to unmount all mounted volumes on disk0 and disk1 (first the CoreStorage volume, which has its own disk identifier (e.g. disk3) but resides on disk0 and disk1) then all other Fusion Drive disks (assuming disk0 = SSD/disk1 = HHD. Please check the diskutil list output for the proper disk identifiers and replace them in the commands below if necessary):
```
diskutil umountDisk /dev/disk3
```
then additional disks. Example:
```
diskutil umountDisk /dev/disk0
diskutil umountDisk /dev/disk1
```
Remove the second EFI partition (assuming the 103 MB partition has the index number 4 in the gpt listing you got earlier)
```
gpt remove -i 4 /dev/disk1
```

Remount all disks in the reverse order

diskutil mountDisk /dev/disk0
diskutil mountDisk /dev/disk1
diskutil mountDisk /dev/disk3

Since any blocking partition is deleted you may now resize the CoreStorage volume with
```
diskutil cs resizeStack LVUUID size 
```
in your example that's
```
diskutil cs resizeStack 5E88EF38-D2A8-4A7D-8508-5C24D948877D 1100g 
```
to expand it to ~1,1 TB (or 1100 GB) or
```
diskutil cs resizeStack 5E88EF38-D2A8-4A7D-8508-5C24D948877D 0g 
```
to expand it to the full available size (0g is a magic number here).

The Recovery HD partition (disk1s3) will be moved to the end of disk1 automatically.
Quit Terminal and reboot to Macintosh HD

IMac – How to re-fuse an unfused Fusion Drive, ideally without formatting

If your disks or volumes don't have a second problem the following steps should work:

Backup your main system volume
Boot to Recovery Mode
Open in the menubar Utilities > Terminal
Get an overview with diskutil list and diskutil cs list
Below I assume the SSD is disk0 and the HDD disk1 (compare the sizes)
Check all important volumes and drives with diskutil verifyDisk diskX and diskutil verifyVolume diskXsY. If necessary repair the disks and volumes.
Revert the CoreStorage LVG (SSD) to a normal partition setup:
```
diskutil cs revert lvUUID
```
This may fail because an lvUUID doesn't exit - then you have to try to delete the Logical Volume Group.
```
diskutil cs delete lvgUUID
```
This may fail also - then you have to "hard-reset" the SSD's partition table by repartitioning it. Finally check with diskutil cs list that no Logical Volume Group exists.
Convert your main system volume (disk1s2) to a CS Logical Volume Group:
```
diskutil cs convert disk1s2
```
Your data will be preserved. This will assign new UUIDs to the (new) LVG, PV, LVF and the LV.
Add disk0s2 as a Physical Volume to the LVG:
```
diskutil cs addDisk lvgUUID disk0s2
```
Resize the Logical Volume with:
```
diskutil cs resizeVolume lvUUID 0g
```
Reboot

with lvUUID = UUID of a Logical Volume; lvgUUID = UUID of a Logical Volume Group. The command diskutil cs addDisk ... is undocumented but works in Sierra.

The approach may fail because other (unknown) obstacles exist. In my VM it worked.

Best Answer

Related Solutions

Messed up 1TB Fusion Drive Partitions (on iMac 5K)

IMac – How to re-fuse an unfused Fusion Drive, ideally without formatting

Related Question