How do I create and mount a fake block device (using a large file/disk image) that passes as a legitimate unformatted disk?
I don't have any spare disks I can use, so I thought: Why don't I just create a loopback device and use that?
Since my host OS disk has plenty of free space I should be able to create a large file on there and mount that as a loopback device.
There are two problems with this (as I understand it):
- Loopback devices have to be formatted with some sort of filesystem in order to be mounted, which will not work with Ceph since Ceph requires an unformatted blockdevice
- Loopback devices do not seem to count as block devices. Ceph docs use
lsblk -fto test if a device is eligible for Ceph. The device has to show up in the output AND not have any filesystem formatted on them.