**Edit** > **I could find a solution** to how recreate a fusion drive and a "Macintosh HD" volume so that OS X can be reinstalled. **I suggest to > people facing similar issue to simply read the answer** that I posted > to my own question, which will provide them a **step by step > procedure**. - - - I need to reinstall MacOS X Mojave on an iMac iMac 27'' 2019 (A2115 EMC 3194). Because of corrupted fusion data structures, the fusion drive was not visible from the installer, so that I had to reset the SSD and HDD: - dd if=/dev/zero of=/dev/disk0 (fully wipes the SSD) - dd if=/dev/zero of=/dev/disk1 count=1 (wipes MBR of HDD) Above commands made both drives visible from the Disk Utility. (They were previously hidden by the Fusion drive container.) Then, from the Disk Utility, the two drives were erased and formatted in APFS, with GPT partition scheme. Strangely, diskutil resetFusion detects the logical volumes from the SSD and HDD but is unable to detect the solid state drive as a physical drive. (The order of disks is inverted here, but we see that the disk1 of the SSD is not listed.) -bash-3.2# diskutil resetFusion Internally-located hardware disk device known to the currently-running macOS: Rotational (disk0) Volumes exported by partitions or storage systems hosted on the above device: SSD SM0032L (disk3s1) HDD ST1000DM003 (disk4s1) Your computer must have exactly 1 solid-state and 1 rotational disk drive **How to fuse the APFS partitions ?** Here's the current scheme. -bash-3.2# diskutil list /dev/disk0 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI EFI 209.7 MB disk0s1 2: Apple_APFS Container disk4 1000.0 GB disk0s2 /dev/disk1 (internal): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme 28.0 GB disk1 1: EFI EFI 314.6 MB disk1s1 2: Apple_APFS Container disk3 27.7 GB disk1s2 /dev/disk2 (disk image): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme +2.1 GB disk2 1: Apple_HFS macOS Base System 2.0 GB disk2s1 /dev/disk3 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +27.7 GB disk3 Physical Store disk1s2 1: APFS Volume SSD SM0032L 20.5 KB disk3s1 /dev/disk4 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +1000.0 GB disk4 Physical Store disk0s2 1: APFS Volume HDD ST1000DM003 20.5 KB disk4s1 (...) Should I use logical volume commands, delete the synthetized volumes of disks 3 and 4 and then create from the command line the volume of disk3 according to the original scheme here below? I know how to use gpt commands to show and edit the gpt tables. Here was the original situation: -bash-3.2# diskutil list /dev/disk0 (internal): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme 28.0 GB disk0 1: EFI EFI 314.6 MB disk0s1 2: Apple_APFS Container disk3 27.7 GB disk0s2 /dev/disk1 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk1 1: EFI EFI 209.7 MB disk1s1 2: Apple_APFS Container disk3 1000.0 GB disk1s2 /dev/disk2 (disk image): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme +2.1 GB disk2 1: Apple_HFS macOS Base System 2.0 GB disk2s1 /dev/disk3 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +1.0 TB disk3 Physical Stores disk0s2, disk1s2 1: APFS Volume Preboot 185.9 MB disk3s2 2: APFS Volume Recovery 510.6 MB disk3s3 3: APFS Volume VM 2.1 GB disk3s4 (...)

Currently, my iMac has no active macOS on it. And the Fusion Drive shows up as two volumes. I am trying to come up with ways to fix the Fusion Drive, install macOS on it(but then how to make Fusion Drive APFS to make it usable as a boot drive for macOS without destroying the logical volume structure?), and then partition the Fusion Drive into three partitions. Environment: 11.5 GB partition on SSD, main contents are a base macOS recovery image (internet installer) and macOS install drive (Catalina). The rest of the SSD is a free partition (formatted in APFS). All of HDD is a free partition (formatted in APFS). Currently, I tried: 1. Fixing my Fusion Drive, then partitioning it. (Partition Fusion Drive breaks its ability to be a valid install drive for macOS, also unknown if the corestorage system still works after being partitioned.) 2. Add multiple volumes into a logical volume group to achieve multiple drives. (Currently not possible, requires older versions of diskutil.)

I have 2014 Mac Mini with fusion drive running Catalina. If I replace original fusion SSD with bigger one, can I restore Time Machine backup or reinstall OS?

I am trying to change the secure boot settings so that I can allow booting from an external disk. Normally to do this you would go into recovery mode with command + r and then change the settings. When I try to do this, however, my mac decides to boot up using recovery mode with internet, in which I cannot change the secure boot settings from. After doing a little research, this seems to be because my Mac has a fusion drive, which is causing the regular recovery mode to not start up. My question is: how do I get into regular recovery mode on a fusion drive Mac? If I can’t, how do I change the secure boot settings without going into recovery mode?

Can you add another disk to a Fusion Drive after it has already been created? Say I had a M1 Mac Mini with 256GB SSD and I made a Fusion Drive using 64GB of the internal SSD with an 8TB external HD (e.g. WD My Book). Would I be able to add another 8TB external to the Fusion Drive after it is full?

I have a late 2015 27'' iMac with 1TB Fusion Drive. Normally I was using my macOS through an SSD connected to the USB and I was sooo happy about the performance of my computer. One day it restarted itself while in sleep mode and... never be able to start again; Symptoms: Apple logo appears when I connect my iOS containing external SSD, but the progress bar never fills up (it stays blank forever) Question mark appears when I do not connect my external SSD with iOS. Command+R does not work and OPT+Command+R do not continue after some point during start up Apple diagnostics say my computer is ok I resetted my NVRAM and tried all possible startup key combinations including Command+S (I cannot reach to Terminal (some weird data log appears and no place to write a command) Apple authorized service cannot do anything since my computer is considered as vintage I talked to the apple expert, and he said most probably my HDD is dead (it is silent now and I do not hear it anymore). Do above symptoms root from the dead HDD?, even all my iOS data is in my external SSD? Will replacing my internal HDD to a new internal SSD solve the problem? I cannot split my Fusion Drive since I cannot reach to the Terminal app, will that be a problem? What symptoms do you think I will have right after replacing my HDD with a new Sata3 SSD? I like my computer and want it back, thanks to all in advance

I attempted to activate FileVault on a late-2013 iMac, which has a 1TB Fusion Drive. However, the encryption process became stuck after several hours, so I had to reboot. This is when the issue started. The computer is running Catalina, which means the file system is APFS. **the issue** Let's fast forward a bit... When I attempt to boot the iMac now, I can reach the login screen. However, after entering the password, it displays the following screen (after approximately 30 seconds of loading time): In recovery mode, the Mac Disk Utility app indicates that the Fusion drive is split. To resolve the issue, it suggests resetting the drive. However, I would prefer an option where I can repair the drive. This is not an easy issue, but if someone could help, I would be grateful! **commands**

-bash-3.2# diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS                         121.1 GB   disk0s2

/dev/disk1 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                                                   *1.0 TB     disk1

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *61.5 GB    disk2
   1:                  Apple_HFS Install macOS Catalina  61.5 GB    disk2s1

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *4.0 GB     disk3
   1:        Apple_partition_map                         4.1 KB     disk3s1
   2:                  Apple_HFS                         2.5 MB     disk3s2

/dev/disk4 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +2.1 GB     disk4
   1:                  Apple_HFS macOS Base System       2.0 GB     disk4s1

/dev/disk5 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +10.5 MB    disk5

/dev/disk6 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +10.5 MB    disk6

/dev/disk7 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk7

/dev/disk8 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk8

/dev/disk9 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk9

/dev/disk10 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk10

/dev/disk11 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk11

/dev/disk12 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk12

/dev/disk13 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +12.6 MB    disk13

/dev/disk14 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +4.2 MB     disk14

/dev/disk15 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +1.0 MB     disk15

/dev/disk16 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk16

/dev/disk17 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk17

/dev/disk18 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk18

/dev/disk19 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk19

/dev/disk20 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +1.0 MB     disk20

/dev/disk21 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk21

/dev/disk22 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +6.3 MB     disk22

/dev/disk23 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +6.3 MB     disk23

/dev/disk24 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk24

/dev/disk25 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk25

-bash-3.2# diskutil apfs list
No APFS Containers found

-bash-3.2# gpt -r -vvv show /dev/disk0
gpt show: /dev/disk0: mediasize=121332826112; sectorsize=512; blocks=236978176
gpt show: /dev/disk0: PMBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: GPT partition: type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, start=40, size=409600
gpt show: /dev/disk0: GPT partition: type=7C3457EF-0000-11AA-AA11-00306543ECAC, start=409640, size=236568496
gpt show: /dev/disk0: Sec GPT at sector 236978175
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34          6         
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     409640  236568496      2  GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC
  236978136          7         
  236978143         32         Sec GPT table
  236978175          1         Sec GPT header

-bash-3.2# gpt -r -vvv show /dev/disk1
gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512; blocks=1953525168
gpt show: /dev/disk1: MBR not found at sector 0
gpt show: /dev/disk1: Pri GPT at sector 1
gpt show: /dev/disk1: GPT partition: type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, start=40, size=409600
gpt show: /dev/disk1: GPT partition: type=7C3457EF-0000-11AA-AA11-00306543ECAC, start=409640, size=1953115488
gpt show: /dev/disk1: Sec GPT at sector 1953525167
       start        size  index  contents
           0           1         
           1           1         Pri GPT header
           2          32         Pri GPT table
          34           6         
          40      409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
      409640  1953115488      2  GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC
  1953525128           7         
  1953525135          32         Sec GPT table
  1953525167           1         Sec GPT header

-bash-3.2# fdisk /dev/disk0
Disk: /dev/disk0	geometry: 14751/255/63 [236978176 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE 1023 254  63 - 1023 254  63 [         1 -  236978175] 
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused

-bash-3.2# fdisk /dev/disk1
Disk: /dev/disk1	geometry: 121601/255/63 [1953525168 sectors]
Signature: 0xBB55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE 1023 254  63 - 1023 254  63 [         1 - 1953525167] 
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused

I can also share hexdump if needed.

This time last Christmas my fusion hard drive stopped working. It had been loud and the back of the iMac (Retina 5K, 27-inch, Late 2015) was burned. After eventually installing the macOS onto the 121.3 GB hard drive. I see plenty of threads stating to reset my hard drives back into one, but I have tried that unsuccesfuly and also I wish to get my files back. I understand the mechanical failure however I would like to try everything before giving up on this. I have see videos on how to get the hd out of the iMac and connect this to another computer, also using another iMac and thunderbolt cable to locate the files, all the way to software apps that can do deep dives. My question is, if the mac can't see the fusion drive anymore then nothing can and surely it's a mechanical failure and the only possible fix would be to take out the hard drive and hope its a pin or connection issue. I'd much prefer to do this in the sofware, however. Please see below and ignore the Seagate external hard drive (which is also coincidentally 2Tb and caused me much initial confusion). I'm still missing the fusion hd. If it's a total lost cause I guess I'll just try and reset them or give up on my 2Tb of hard space. Many thanks for any assistance.

Coworker has an Acasis NVMe enclosure with a 1TB NVMe. Speeds are about 3000MB/s on USB4. The thing is that he has lying around a 8TB HDD 2.5 from an old PC. It would be awesome to use both as “Fusion drives” by connecting them to his Mac Studio M2. The question is if macOS Ventura supports this kind of arrangement. He uses it for video editing. The idea is to copy source files overnight to the Fusion Drive and work from there instead of reading from the office NAS (local is fine with 2.5Gb, but WFH is unbearable at 150Mb~ tops plus latency).

My issue is similar to this one, https://apple.stackexchange.com/questions/377314/bootcamp-says-disk-could-not-be-partitioned-on-catalina-version-10-15-2?newreg=e8352423341a47889514bd05fa4d7186 I'm on a 2019 iMac i9 27" with a 3TB Fusion that's been formatted with Catalina and APFS from the beginning, but I *have* successfully installed Bootcamp and removed it. Now I'm trying to play games that don't work in a VM and want it back. Bootcamp is failing to create the partition and corrupting the APFS container as it unwinds. Actually, it's creating the partitions but gacking at some point. The question above has the fsck_apfs commands I've been looking for, but I'm looking beyond that. What if, prior to reloading, I created the APFS container AND a smaller HPS/NTFS/FAT32 partition for Bootcamp Assistant to use? A "sacrifice" disk if you will. Does it matter if the partition is created first, in the first sectors of the drive or at the end behind the APFS container? This time, I plan to only do a MacOS install and not a recovery to test if this works. If so, I'll either restore directly to it or blow everything away again and do a full restore from the ground up with the extra partition.

I'm upgrading from FusionDrive to a regular drive (or a dual-drive setup). Is there any difference as compared to regular HDD -> SSD upgrade *specifically in terms of* inheriting pre-upgrade set of Time Machine backups and using the same Time Machine volume for future backups incrementally? In case it matters: post-upgrade boot drive will be a fully restored replica from FusionDrive-time backup on Time Machine. ---- In my particular case I'm on 2017 27" iMac, Mojave 10.14.6.

Here I have a "fusion" apfs container disk5 made from 2 partitions of physical disks. 1) I want to add a new /dev/disk6 (/dev/disk6s2) which is a 8TB disk to be used in logical disk disk5. 2) Then I want to remove disk4s2 from being part of disk5. At the end I should have a disk5 of size 9TB. All this because I want to decommission disk4 transparently for the logical volumes that exist on disk5. --> so I do not want to create a new 9TB apfs container. How to do that ? (I did a similar operation recently on a Linux host with LVM and pvmove to move physical extends, and stop using the disk I wanted to decommission, then de registering it from the VG. It was fairly simple). From Apple diskutil documentation, I can't find out how to do sush operation as 1) and 2). $diskutil list

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk5         1000.0 GB  disk0s2
.
.
.

/dev/disk4 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk4
   1:                        EFI EFI                     209.7 MB   disk4s1
   2:                 Apple_APFS Container disk5         4.0 TB     disk4s2

/dev/disk5 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +5.0 TB     disk5
                                 Physical Stores disk4s2, disk0s2

$diskutil apfs list

APFS Containers (2 found)
|
+-- Container disk5 33333333-3333-3333-3333-333333333333
|   ====================================================
|   APFS Container Reference:     disk5 (Fusion)
|   Size (Capacity Ceiling):      5000572403712 B (5.0 TB)
|   Capacity In Use By Volumes:   3970267238400 B (4.0 TB) (79.4% used)
|   Capacity Not Allocated:       1030305165312 B (1.0 TB) (20.6% free)
|   |
|   +-< Physical Store disk0s2 22222222-2222-2222-2222-222222222222
|   |   -----------------------------------------------------------
|   |   APFS Physical Store Disk:   disk0s2 (Main, "Faster" Disk Use)
|   |   Size:                       999995129856 B (1000.0 GB)
|   |
|   +-< Physical Store disk4s2 11111111-1111-1111-1111-111111111111
|   |   -----------------------------------------------------------
|   |   APFS Physical Store Disk:   disk4s2 (Secondary, Designated Aux Use)
|   |   Size:                       4000577273856 B (4.0 TB)
.
.
.

> *Question renamed from:* « **Diagnosing what's going wrong with the fusion drive of an iMac 27'' 2019 A2115 EMC 3194** » *after the origin of the problem could be located*. Having a **non-booting iMac using fusion drive**, with a 32GB SSD and 1TB HDD, I would like attempt restoring it without loosing the data. I can still start the iMac in recovery mode and issue commands through the terminal. **I did two external clones of both the SSD and HDD**. There were no errors during the cloning. Furthermore the sha1 /dev/... command confirmed identical SHA1 hashes for the original disks and their clones. So, **I can restore the situation by cloning in the other direction if necessary**. -bash-3.2# diskutil list /dev/disk0 (internal): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme 28.0 GB disk0 1: EFI EFI 314.6 MB disk0s1 2: Apple_APFS Container disk3 27.7 GB disk0s2 /dev/disk1 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk1 1: EFI EFI 209.7 MB disk1s1 2: Apple_APFS Container disk3 1000.0 GB disk1s2 /dev/disk2 (disk image): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme +2.1 GB disk2 1: Apple_HFS macOS Base System 2.0 GB disk2s1 /dev/disk3 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +1.0 TB disk3 Physical Stores disk0s2, disk1s2 1: APFS Volume Preboot 185.9 MB disk3s2 2: APFS Volume Recovery 510.6 MB disk3s3 3: APFS Volume VM 2.1 GB disk3s4 (...) diskutil verifyDisk /dev/disk1 reveals that **the problem comes from the EFI partition on the mechanical hard drive**: This first problem could be corrected. See "Edit" section below. -bash-3.2# diskutil verifyDisk /dev/disk1 Started partition map verification on disk1 Checking prerequisites Checking the partition list Checking the partition map size Checking for an EFI system partition Checking the EFI system partition's size Checking the EFI system partition's file system Problems were found with the partition map which might prevent booting Error: -69766: The partition map needs to be repaired because there's a problem with the EFI system partition's file system Underlying error: 8 I assume that I should destroy the GPT of the HDD and create it again, or at least modify it. In David Anderson's answer here , one can see how to remove GPT entries and create ones. But **I am not sure if I should create again the GPT of the HDD with the same values or if some have to be corrected**. Here's the output of gpt -r show disk1 for the HDD: gpt -r show disk1 start size index contents 0 1 PMBR 1 1 Pri GPT header 2 32 Pri GPT table 34 6 40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B 409640 1953115488 2 GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC 1953525128 7 1953525135 32 Sec GPT table 1953525167 1 Sec GPT header --- **Edit** I deleted the EFI partition and created it again. diskutil info disk1s1 (and made screenshot of partition info) diskutil umountDisk disk1 (unecessary, but just to be sure) gpt remove -i 1 /dev/disk1 gpt add -i 1 -b 40 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B /dev/disk1 gpt -r show disk1 (verify gpt table) diskutil info disk1s1 (verify that the partition is still FAT32 and EFI diskutil verifyDisk /dev/disk1 (verify partition map on disk1) The partition map is now OK for disk1. The verification fails on the verification of the volume, on disk0s2: error: fusion_mid_tree: btn: invalid o_oid (0x0) Fusion data structures are invalid The volume /dev/disk0s2 could not be verified completely Storage system check exit code is 8 Error: -69716: Storage system verify or repair failed Underlying error: 8 When calling diskutil resetFusion (the iMac seems using Mojave), only the rotational disk (HDD) is detected: diskutil resetFusion Internally-located hardware disk device known to the currently-running macOS: Rotational (disk1) Volumes exported by partitions or storage systems hosted on the above device: Your computer must have exactly 1 solid-state and 1 rotational disk drive. In summary, the problem seems coming from the fact that **although the SSD is listed by diskutil, it is is ignored for the fusion drive**. So, the question is **how to repair the fusion data structures**? ---

Reference old question: https://apple.stackexchange.com/questions/458800/2013-imac-with-apfs-fusion-drive-fails-to-boot-how-to-recover-data/459970#459970 I have removed both the SSD drives from the iMac. Purchased a new Mac Mini M2 running macOS Ventura 13.3. I bought a caddy to plug the 128GB SSD via USB port on the Mac Mini. Likewise, I purchased a caddy to plug the 2TB HDD into Mac Mini via USB port. Rebooted the Mac Mini. The good news is that I can see the drive as Fusion on desktop. I can see the directory structure but I am unable to copy the data from the 2TB HDD. Can somebody help? The drive itself shows no hardware issues. Terminal -- diskutil list output /dev/disk7 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *121.3 GB disk7 1: EFI EFI 209.7 MB disk7s1 2: Apple_APFS Container disk8 121.1 GB disk7s2 /dev/disk8 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +2.1 TB disk8 Physical Store disk7s2 1: APFS Volume Fusion - Data 2.0 TB disk8s1 2: APFS Volume Preboot 25.8 MB disk8s2 3: APFS Volume Recovery 526.8 MB disk8s3 4: APFS Volume VM 2.1 GB disk8s4 5: APFS Volume Fusion 11.2 GB disk8s5 The interesting part is that I suspect is the the two drives are not properly fused /dev/disk8 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +2.1 TB disk8 Physical Store disk7s2 I would expect from the Physical store to have disk7s2 and disk8s1. When I click on the disk icon on the desktop "Fusion" I can see the directory structure and files in the folders. However when I copy the folder I get error and Zerro Bytes files are copied. I have tried coping the files using the terminal windows CP source to target directory same issue as GUI command. Calling all people who can help. Somebody must know of a way how I can copy the data to another drive. I would be grateful if someone could help. If you need any additional information do let me know and I will post the updates. Apologies I don't have a backup. so recovering the data is the only option I have. trying to find a way I can do it using the help of this group and without the need for professional data recovery people. I have not deleted any files, Neither formatted the drive. I did try some free trial utility and no data was recovered. I feel the fuse drive needs something to glue it back. As the data is on the disk.

I have an iMac with a broken motherboard. I got the HDD out of it and I now want to view my files on my Mac M1 device. It shows my external device on Disk utility, but I'm unable to view the device through finder? I know the old device is an HFS+ and my new Mac M1 is AFPS. It was a fusion disk, like I said, I can't use the motherboard any more. The tool/cable etc to read the HDD works. This is what I see in Disk utility Not sure if it was encrypted. Disk Drill can scan the documents, so there must be a way that I can view them through other ways that don't require me to pay 300$. I was also able to remove the PCIe SSD from the iMac and figuring out how to connect this to my Mac M1 via USB. If I where to attach them both to my MacOs would read them as a fusion drive through help of a software?

I have a 2019 iMac 21.5" which has a 1TB fusion drive. But the HDD is getting old and slow (and it obviously wasn't fast to begin with). Until recently, I also had Windows Bootcamp installed on the HDD, and it was horribly slow. To fix this, I bought an external SSD and now I boot Windows 11 on it via EFI. It's so fast, it's actually better than using my Mac partition. So I want to make the Mac side faster by doing a clean install of MacOS Big Sur to the 28GB SSD and then partition the new 480GB SSD: 240GB for Windows 11, and 240GB for Mac applications and commonly accessed data when running MacOS. This leaves the 1TB HDD for storage of files/application I use rarely. I assume I want to install MacOS on the 28GB SSD because my new SSD has a speed of 600 MBps and is connected via USB 3.0, is that even slower? So I believe the internal one is faster. However, I have a few things I don't quite understand about how everything is structured on a Mac. If I was to split my fusion drive, and then install MacOS to the 28GB SSD. How do I tell the Mac I want to use the external 240GB partition for Applications, Library, System, and Users? I assume having these on SSD will speed up my Mac (please correct me if I'm wrong). I'm also very confused about what the Macintosh HD/System folder actually is and how this fits into what I want to do. I want to know exactly what I need to do before I attempt this. Any help would be greatly appreciated.

My iMac 21.5 inch 4k (late 2015) has been abnormally slow during regular use, so I used Drive Dx to diagnose it. I get a "failing" status on the report, which is understandable. The first thing I did after seeing this was make a backup using Carbon Copy Cloner. Note that prior to this backup process, the 24 GB "blade" SSD and 1TB HDD were used together as a Fusion drive (1.02 TB) and were *not* split. It showed as 1 drive under About This Mac > Storage, and under disk utility but I could see the 24 GB SSD using diskutil list. My external SSD now has a full copy of my computer, which is good, but I'm not quite sure how to go about restoring it. If I remove the 1TB HDD and replace it with an SSD, it wouldn't make sense to do diskutil resetfusion and make use of the 24 GB blade SSD, correct? Here is what I would normally do for a clean install: 1. Replace 1TB HDD with the appropriate SSD 2. Go into recovery mode (Cmd+R or Cmd+Opt+R), erase and format the SSD to APFS or MacOS extended (journaled) 3. Choose "Reinstall macOS" 4. When macOS boots, locate the SSD under "Transfer information to this Mac". Something like this: ![Screenshot of the 'Transfer Information to This Mac' window ][1] There seems to be missing intermediate steps since the external backup is a clone of the fusion drive which contains the data on the 24 GB blade. By the way, I'm pretty sure the external backup is not bootable, since I just used CCC's default backup task for copying the filesystem. I will definitely experiment a bit once I get the kit and the SSD, but I wanted to prepare for it and get some advice in advance. Note: I did find this post about cloning a Fusion drive and restoring to a new SSD, but was still unsure of what happens to the data from 24 GB blade. **Update**: Just make a time machine backup to an external ssd, install the new internal ssd and restore the backup after macOS installs. The 24gb blade ssd shouldn't cause any issues in the restore process since they are no longer "fused" I think. I've heard people booting from that 24gb ssd and storing data on the newly installed ssd so that's definitely an option instead of leaving it unused(?)

My 2 TB Fusion drive has become a SATA Drive of 2 TB. I have an IMac 27 inch late 2015 with a 2 TB Fusion drive. After an update my computer crashed. I had to install the OS X from the OS that came with the IMac. I have updated everything to OS Catalina 10.15.7 and i use the Time machine back up to restore. But when i started the IMac i noticed that everything was soo slow.. `everything works slow. Opening apps, opening windows...slow. And then i noticed that my Fusion drive was a SATA drive! If u go to about this mac and then go to 'storage'. then u see that it is an SATA drive instead of Fusion. What can be happened? Is this why my. machine is so slow? Does the IMac not see the Fusion drive? ( i can't upload pictures here?..)

My 2015 (Model 17,1 w/OS X 10.14 Mojave) iMac was purchased new in 2017. It was a great system until its Fusion Drive failed. After two unsuccessful attempts to repair the Fusion Drive, I am now concerned whether or not this iMac is [reparable](https://www.merriam-webster.com/dictionary/reparable) : Apple declined to repair a "vintage" iMac, and the "repair" performed by a specialist Mac repair shop was an expensive failure. The [repairability](https://en.wikipedia.org/wiki/Repairability) issue seems to be largely due to Apple's proprietary SSD designs. For some models, one can find 3rd party replacement SSDs, but for other models, compatible repair parts are not available from any source. For example, OWC - the primary 3rd party source for replacement SSDs for Apple products - [does not make an SSD compatible with my iMac Model 17,1.](https://i.sstatic.net/kOMUG.png) Some have suggested that a simpler solution to repair a Fusion Drive is simply to replace it with a single, ***non-Fusion*** SSD connected to the iMac's internal SATA cabling. This strikes me as an ideal solution - assuming there are no *awkward* tradeoffs. This question(s) is intended to discover what - if any - tradeoffs are required for the ***non-Fusion*** repair option. It's highly likely I do not know what these tradeoffs might be, so I'll list the ones I can think of & ask those providing *answers* to list any others they're aware of. Potential tradeoffs & questions for a non-Fusion repair option: * Performance: I'm not very concerned about reductions in classic storage drive performance. [SATA3 is never going to equal PCI data rates](https://www.makeuseof.com/tag/pcie-vs-sata-type-ssd-best/) , but the **performance limitations** I want to overcome are those that require 60 seconds for a login, and 30 second delays in launching an app! * **Question 1:** Will the ***non-Fusion*** repair option eliminate the horribly sluggish performance I see now? * **Question 2:** My Time Machine backup was done on the system when it had a Fusion Drive. Will this backup restore to the ***non-Fusion*** system? * **Question 3:** Should the SSD portion of the Fusion Drive be removed from the system, should it remain - or does it make any difference? * **Question 4:** Do you know of any other likely tradeoffs or artifacts wrt a ***non-Fusion*** system?

I [have read](https://iboysoft.com/wiki/apfs.html#can-you-use-apfs-on-hdd?) that APFS was *optimized* for SSDs, but that it's not an optimal choice[ for HDDs. However, I just got my iMac (Model 17,1; OS X Mojave, 10.14) back from repair, and both drives are formatted as APFS. I checked a [diskutil output](https://apple.stackexchange.com/questions/446755/imac-mojave-suddenly-became-extremely-slow-on-login) made before the repair work was done (i.e. as it came from the factory), and it seems that both drives were APFS when my iMac was originally built. Is the APFS format on the HDD in a Fusion Drive a necessity (perhaps due the the need for the SSD using APFS)? If not, could performance/stability be enhanced by using HFS+ on the HDD? RE: "Has it been reformatted as a Fusion Drive?" The diskutil list output:

necromac:~ seamus $ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk2         500.1 GB   disk0s2

/dev/disk1 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *3.0 TB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                 Apple_APFS Container disk2         3.0 TB     disk1s2

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +3.5 TB     disk2
                                 Physical Stores disk0s2, disk1s2
   1:                APFS Volume Macintosh HD            139.3 GB   disk2s1
   2:                APFS Volume Preboot                 52.0 MB    disk2s2
   3:                APFS Volume Recovery                510.6 MB   disk2s3
   4:                APFS Volume VM                      2.1 GB     disk2s4

... and diskutil screenshots: | Screenshot | Screenshot | | -------- | -------------- | ||| || empty|