diskutil coreStorage in Lion fails to create a concatenated LVG, error -69886 I would like to create a logical volume group (LVG) with two physical disks.

Issue

The command: 

diskutil coreStorage create LVGNAME /dev/disk1 /dev/disk2  

returns:  

Started CoreStorage operation  
Error: -69886: Invalid request


More info

Tested with two USB drives, two SATA disks (one internal, one external FireWire 800).  

I can format them with Disk Utility.

I can unmount without a problem. 

MacBookPro8,2 with Mac OS X 10.7.4 (same with 10.7.5)

diskutil cs list
No CoreStorage logical volume groups found


With one disk alone I can create a non-composite LVG:

diskutil coreStorage create LVGNAME /dev/disk1  
Started CoreStorage operation  
Unmounting disk1  
Repartitioning disk1  
Unmounting disk  
Creating the partition map  
Rediscovering disk1  
Adding disk1s2 to Logical Volume Group  
Creating Core Storage Logical Volume Group  
Switching disk1s2 to Core Storage  
Waiting for Logical Volume Group to appear  
Discovered new Logical Volume Group "05F84BFF-DC4D-4DD2-94DB-116FC7F8C804"  
Core Storage LVG UUID: 05F84BFF-DC4D-4DD2-94DB-116FC7F8C804  
Finished CoreStorage operation
Operating system

Can you reproduce the problem with Mac OS X 10.7.5? 

If -69886 arises from a failure to unmount

Expanding upon a hint in an answer to a linked question, try this before the Core Storage operation … for the device that apparently can't be added: 

diskutil unmount /dev/disk2s2

– then if the unmount fails, to discover what's open: 

sudo lsof /dev/disk2s2

Reference

Currently limited by Apple to Mac OS X 10.7.4: diskutil(8) OS X Manual Page