I have a 5k iMac with a Fusion Drive. I had trouble with macOS, so I reinstalled it, and restored from a Time Machine backup using Migration Assistant.
After that, the system has been very slow, and beachballs all the time. Looking in Disk Utility, I find that the Fusion Drive was destroyed:
Notice that Macintosh HD is within the HDD, and the SSD is unformatted.
Here's the output of
diskutil cs list. It seems that there's already a Core Storage logical volume group, but it's too small (121GB rather than 2.1TB):
CoreStorage logical volume groups (1 found) | +-- Logical Volume Group 7090C28E-A2D2-49C3-BDA4-0B4C96F499B4 ========================================================= Name: Macintosh HD Status: Offline Size: 120988852224 B (121.0 GB) Free Space: -none- | +-< Physical Volume E8FF728C-B2AD-44F5-B9B9-EE0BE22D1782 | ---------------------------------------------------- | Index: 0 | Disk: disk0s2 | Status: Checking | Size: 120988852224 B (121.0 GB) | +-< Physical Volume FCB9BDAF-B3E1-403D-B078-CD967BEDECB3 ---------------------------------------------------- (No properties)
And here's the partition map. Strangely, I have Macintosh HD and EFI partitions on both disks:
$ 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_CoreStorage Macintosh HD 121.0 GB disk0s2 3: Apple_Boot Boot OS X 134.2 MB disk0s3 /dev/disk1 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *2.0 TB disk1 1: EFI EFI 209.7 MB disk1s1 2: Apple_HFS Macintosh HD 2.0 TB disk1s2 3: Apple_Boot Recovery HD 650.0 MB disk1s3
And here's more detailed info about the HDD:
$ diskutil info /dev/disk0s2 Device Identifier: disk0s2 Device Node: /dev/disk0s2 Whole: No Part of Whole: disk0 Volume Name: Macintosh HD Mounted: Yes Mount Point: / Partition Type: Apple_HFS File System Personality: Journaled HFS+ Type (Bundle): hfs Name (User Visible): Mac OS Extended (Journaled) Journal: Journal size 155648 KB at offset 0x3a38000 Owners: Enabled OS Can Be Installed: Yes Recovery Disk: disk0s3 Media Type: Generic Protocol: SATA SMART Status: Verified Volume UUID: 388929F6-08C6-31FF-9AB1-3AB0E5FF1383 Disk / Partition UUID: D3F0C33F-6052-46F9-A4BE-90D4435B183A Disk Size: 2.0 TB (1999404957696 Bytes) (exactly 3905087808 512-Byte-Units) Device Block Size: 512 Bytes Volume Total Space: 2.0 TB (1999404957696 Bytes) (exactly 3905087808 512-Byte-Units) Volume Used Space: 1.3 TB (1325673127936 Bytes) (exactly 2589205328 512-Byte-Units) (66.3%) Volume Available Space: 673.7 GB (673731829760 Bytes) (exactly 1315882480 512-Byte-Units) (33.7%) Allocation Block Size: 4096 Bytes Read-Only Media: No Read-Only Volume: No Device Location: Internal Removable Media: Fixed Solid State: No
And the SSD:
$ diskutil info /dev/disk1s2 Device Identifier: disk1s2 Device Node: /dev/disk1s2 Whole: No Part of Whole: disk1 Volume Name: Not applicable (no file system) Mounted: Not applicable (no file system) File System: None Partition Type: Apple_CoreStorage OS Can Be Installed: No Media Type: Generic Protocol: PCI SMART Status: Verified Disk / Partition UUID: 0993633C-EC5D-473D-AC5A-8CB967E9D532 Disk Size: 121.0 GB (120988852224 Bytes) (exactly 236306352 512-Byte-Units) Device Block Size: 512 Bytes Read-Only Media: No Read-Only Volume: Not applicable (no file system) Device Location: Internal Removable Media: Fixed Solid State: Yes Device Location: "SSD" This disk is a Core Storage Physical Volume (PV). Core Storage Information: PV UUID: E8FF728C-B2AD-44F5-B9B9-EE0BE22D1782 LVG UUID: 7090C28E-A2D2-49C3-BDA4-0B4C96F499B4
diskutil repairDisk works for the HDD (disk0), and doesn't seem to find much to repair. But it flags an error on the SSD (disk1):
$ sudo diskutil repairDisk /dev/disk1 [...] Logical Volume Group 7090C28E-A2D2-49C3-BDA4-0B4C96F499B4 spans 2 devices Incomplete or inconsistent CoreStorage Physical Volume set Storage system check exit code is 1 Problems were encountered during repair of the partition map Error: -69716: Storage system verify or repair failed Underlying error: 1: Operation not permitted
When I run
fsck_cs /dev/disk0, it says that it's not a CoreStorage volume, and likewise for disk1.
Has the Fusion Drive become unfused? How do I re-fuse it?
Ideally without formatting or reinstalling macOS? I'll backup just in case, but I hope not to use it.
I looked at
diskutil mergePartitions ..., but it seems to work only for partitions on the same physical disk. Is there another way?
Ideally using free software, but I'm willing to pay if needed.
This is on Sierra, 10.12.1.