After replacing the SuperDrive in my MacBook Pro I copied the Recovery HD to a USB stick and booted from it. Then I ran diskutil cs create MacintoshFusionDrive /dev/disk0 /dev/disk1
(SSD, HDD), reinstalled MacOS from the stick and migrated from my backup.
Unfortunately, I didn't think about keeping the Recovery HD, so I ran from the stick diskutil cs resizeVolume
on the logical volume and diskutil cs resizeDisk <UUID> <size> "Recovery HD" <size>
on the coreStorage disk of the HDD to make a new partition on wich I then copied the contents of my recovery stick.
Somehow the name of the recovery partition only in the startup menu (alt boot) was localized in German but I got rid of that by running sudo bless --folder /Volumes/Recovery\ HD -label Recovery\ HD
. I don't really understand why this happened and how that exact line solved problem. But all seem's fine now. Perhaps I accidentally copied the image on the drive back to the drive directly. Anyhow.
It remains to resolve the last oddity that in the startup hdd menu, there are two Fusion Drive
s wich both start up the system just fine. It's not a real problem but I would like to know what's causing this and how to get rid of the duplication.
$ diskutil cs list
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 3D7E41ED-2D3B-4C46-A696-2C0C156B6BF6
=========================================================
Name: MacintoshFusionDrive
Status: Online
Size: 625672790016 B (625.7 GB)
Free Space: 154107904 B (154.1 MB)
|
+-< Physical Volume B7097B08-1AD3-4AAA-BD1B-88BF5E0EF57E
| ----------------------------------------------------
| Index: 0
| Disk: disk0s2
| Status: Online
| Size: 127691702272 B (127.7 GB)
|
+-< Physical Volume 12F98EE5-AE4C-4A14-8276-7915BCD06999
| ----------------------------------------------------
| Index: 1
| Disk: disk1s2
| Status: Online
| Size: 497981087744 B (498.0 GB)
|
+-> Logical Volume Family 5E001AF2-DE08-46C2-A1DA-5637AB534553
----------------------------------------------------------
Encryption Status: Unlocked
Encryption Type: None
Conversion Status: NoConversion
Conversion Direction: -none-
Has Encrypted Extents: No
Fully Secure: No
Passphrase Required: No
|
+-> Logical Volume AC804BCD-419F-4AA0-AE01-1C7D25FF3949
---------------------------------------------------
Disk: disk2
Status: Online
Size (Total): 619999997952 B (620.0 GB)
Conversion Progress: -none-
Revertible: No
LV Name: Fusion Drive
Volume Name: Fusion Drive
Content Hint: Apple_HFS
$ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *128.0 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_CoreStorage 127.7 GB disk0s2
3: Apple_Boot Boot OS X 134.2 MB disk0s3
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_CoreStorage 498.0 GB disk1s2
3: Apple_Boot Boot OS X 650.0 MB disk1s3
4: Apple_Boot Recovery HD 1.1 GB disk1s4
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS Fusion Drive *620.0 GB disk2
$ sudo 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 972619312 2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
973028952 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
974298488 2212488 4 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
976510976 262159
976773135 32 Sec GPT table
976773167 1 Sec GPT header
$ diskutil info disk1
Device Identifier: disk1
Device Node: /dev/disk1
Part of Whole: disk1
Device / Media Name: Hitachi HTS545050B9SA02 Media
Volume Name: Not applicable (no file system)
Mounted: Not applicable (no file system)
File System: None
Content (IOContent): GUID_partition_scheme
OS Can Be Installed: No
Media Type: Generic
Protocol: SATA
SMART Status: Verified
Total Size: 500.1 GB (500107862016 Bytes) (exactly 976773168 512-Byte-Units)
Volume Free Space: Not applicable (no file system)
Device Block Size: 512 Bytes
Read-Only Media: No
Read-Only Volume: Not applicable (no file system)
Ejectable: No
Whole: Yes
Internal: Yes
Solid State: No
OS 9 Drivers: No
Low Level Format: Not supported
Please let me know, if anything else could be of help.
Best Answer
Had the same question... Fusion Drive utilizes a component of OS X called CoreStorage to work. When you boot your Mac holding down Option, you are booting into a screen running in the low-level EFI environment, before OS X has started. EFI doesn't understand what a home-built Fusion Drive is, but sees two physical drives capable of booting into OS X.
I'm not sure of the mechanics of why factory-built Fusion Drives in the latest Macs act differently but my guess is that there is a firmware chip of some sort, like you said. Apple is known to put custom firmware on some of their hard drives. (Answer taken from another post)