Cache creation failed: get_device for cache device failed.

[f3bruary]

I switched from Windows to Arch Linux and am trying to get SSD caching to work (intel SRT). It's a 500gb HDD with a 32GB SSD (msata).

$ sudo eio_cli create -d /dev/sda -s /dev/sdb -c my_first_enhanceio

Cache Name : my_first_enhanceio
Source Device : /dev/sda
SSD Device : /dev/sdb
Policy : lru
Mode : Write Through
Block Size : 4096
Associativity : 256
[Errno 16] Device or resource busy
Cache creation failed (dmesg can provide you more info)

From dmesg:

enhanceio: Cache creation failed: get_device for cache device failed.

If someone could help me out it would be greatly appreciated.

[f3bruary]

Had to use dmraid to detach /dev/sdb from a raid array I wasn't aware of. Then it worked.