Use --data-dev or --data-dir for ceph-disk parameters to avoid making di...

ceph-disk parameters "--data-dev" or "--data-dir" are useful to avoid making directories such as /dev/sdc my mistake when you want to use a device that does not exist.
You might be right. I don’t see any way we could specify relative paths with ceph-deploy. Maybe I am wrong?

I thought the format was:

ceph-deploy osd prepare $NODE:$DISK

where $DISK=="sdb" or similar for block devices.

where $DISK=="/mnt/sdc" or similar for directory.

What I don’t want is "ceph-disk" to make a directory "/dev/sdf" which it currently does. We could invert add to the logic and assume that if the path starts "/dev/" its a block device.