problem creating fusion drive

[Errz]

when i try to key in disktuil cs create Fusion /dev/disk0 /dev/disk1
i get this error
Started CoreStorage operation
Unmounting disk0
Error: -69888: Couldn't unmount disk

below is the info of diskutil list. SSD not appearing in Disk Utility . i can only see the 1TB drive.

/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *256.1 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_CoreStorage 255.7 GB disk0s2
3: Apple_Boot Boot OS X 134.2 MB disk0s3
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk1
1: EFI 209.7 MB disk1s1
2: Apple_CoreStorage 999.9 GB disk1s2
3: Apple_Boot Boot OS X 134.2 MB disk1s3
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS Macintosh HD *1.2 TB disk2
/dev/disk3
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk3
1: EFI 209.7 MB disk3s1
2: Apple_HFS Clone 499.1 GB disk3s2
3: Apple_Boot Recovery HD 784.2 MB disk3s3

anyone know what's wrong?

 

[philipma1957]

THE 256GB DISK IS THERE


as is the 999gb disk.



why are you keying in anything at all. are you trying to do this via console / terminal commands


or with disk utility . quite frankly the terminal method can fail with just 1 miss stroke of the key board

 

[gtstricky]

I had an issue doing it when booted from one of the drives. I ended up creating a bootable flash drive with disk utility on it and it went smooth as butter.

 

[Errz]

manage to set up the fusion drive.

thanks all!