I've tried looking at the code and I'm not sure what I see. The business bits look like they are in /usr/clearos/apps/storage/libraries/Device_Partition.php and /usr/clearos/apps/storage/libraries/Storage_Device.php. I have not traced through the logic but in Device_Partition.php it looks like the function do_format($device) can only create GPT partitions. Do they work on BIOS systems? The function do_format_partition($partition_id) can only create ext3 partitions
In Storage_Device.php the function create_data_drive($device, $type) can format ext3 and ext4 partitions. It also seems to write a temporary log called storage_create.log to CLEAROS_TEMP_DIR but I can't see where that is specified.
I have not tried to check where these functions are called from.
I am a bit confused by what I see, but then I'm not a PHP programmer.