I own an iMac late 2013 with a fusion drive. Recently I installed Windows 8.1 using Bootcamp on a separate partition on my disk. After a few days, the booting process of OS X started failing and I had to reinstall OS X. I decided to remove the bootcamp partition and start with a fresh installation.
It turned out that my fusion drive (128GB storage) and normal hard disk (1TB storage) were separated so I searched on how to fix this. I'm unable to find the tutorial which I followed back since it is some time ago. Currently, my iMac is quite slow and I was thinking that it might not be using the fusion drive. After running an iostat -d 1
command while writing some data to the disk, it turned out that my fusion drive is not writing anything:
disk0 disk1
KB/t tps MB/s KB/t tps MB/s
4.05 0 0.00 30.48 526 15.64
0.00 0 0.00 9.70 429 4.07
0.00 0 0.00 6.12 328 1.96
0.00 0 0.00 6.99 395 2.70
0.00 0 0.00 8.64 332 2.80
0.00 0 0.00 10.09 480 4.73
0.00 0 0.00 102.38 622 62.18
0.00 0 0.00 97.81 392 37.49
0.00 0 0.00 81.03 248 19.66
0.00 0 0.00 88.55 454 39.29
0.00 0 0.00 237.50 329 76.37
Note that disk0
is my fusion drive and disk1
is my normal hard disk as can be seen in the output from 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 Schijf 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 *1.0 TB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_CoreStorage Schijf 999.3 GB disk1s2
3: Apple_Boot Recovery HD 650.0 MB disk1s3
/dev/disk2 (internal, virtual):
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS Schijf +999.0 GB disk2
Logical Volume on disk1s2, disk0s2
7D5C38D3-6682-498B-A003-82580C9EC3D3
Unencrypted
The output of diskutil cs list
is the following (which I think is right since my fusion drive is part of the CoreStorage volume):
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 654B2807-197B-46D1-9919-B75C0290D33A
=========================================================
Name: Schijf
Status: Online
Size: 1120333979648 B (1.1 TB)
Free Space: 120722538496 B (120.7 GB)
|
+-< Physical Volume B735648A-5545-4004-B9F0-C79F6ECF65EC
| ----------------------------------------------------
| Index: 0
| Disk: disk1s2
| Status: Online
| Size: 999345127424 B (999.3 GB)
|
+-< Physical Volume 6C227359-82B8-4406-BE71-B77B9BEC7F1D
| ----------------------------------------------------
| Index: 1
| Disk: disk0s2
| Status: Online
| Size: 120988852224 B (121.0 GB)
|
+-> Logical Volume Family 82BD1896-F03C-4111-8A01-40EADC2D5E2D
----------------------------------------------------------
Encryption Type: None
|
+-> Logical Volume 7D5C38D3-6682-498B-A003-82580C9EC3D3
---------------------------------------------------
Disk: disk2
Status: Online
Size (Total): 998973898752 B (999.0 GB)
Revertible: No
LV Name: Schijf
Volume Name: Schijf
Content Hint: Apple_HFS
I'm not sure what's wrong here. I would like my fusion drive to work again since the current speed of my computer is quite slower than it was before. Can anyone point me in the right direction? Many thanks!
Best Answer
If you have your data safely backed up or don't care about losing it, you can follow these instructions to recreate your Fusion Drive.
Boot into Internet Recovery or an OS X bootable drive.
From the Utilities menu, open Terminal.
Run
diskutil cs delete 654B2807-197B-46D1-9919-B75C0290D33A
to destroy your current Fusion Drive. This WILL lose all of your data!Run
diskutil list
to get a list of the locations of your current drives.Run
diskutil cs create <whatever you want to name your Logical Volume Group> <mount point of drive 1> <mount point of drive 2>
to create a new LVG.Run
diskutil cs createVolume <whatever your Core Storage LVG UUID, which you'll see in the last lines of the last command's output> jhfs+ "Macintosh HD" 100%>
.Now your computer should see a single virtual hard drive named Macintosh HD. Reinstall OS X on it and then you should be good to go. Good luck!