stgraber@castiana:~$ lxc storage volume create default my-fs size=10GiB
Storage volume my-fs created
stgraber@castiana:~$ lxc storage volume create default my-block size=10GiB --type=block
Storage volume my-block created

stgraber@castiana:~$ lxc storage volume list default
+-----------------+------------------------------------------------------------------+-------------+--------------+---------+
|      TYPE       |                               NAME                               | DESCRIPTION | CONTENT TYPE | USED BY |
+-----------------+------------------------------------------------------------------+-------------+--------------+---------+
| custom          | my-block                                                         |             | block        | 0       |
+-----------------+------------------------------------------------------------------+-------------+--------------+---------+
| custom          | my-fs                                                            |             | filesystem   | 0       |
+-----------------+------------------------------------------------------------------+-------------+--------------+---------+
| image           | a4dc839edd35d50158d57818938775669265a3af004bd93b8281115ee0abd29d |             | block        | 1       |
+-----------------+------------------------------------------------------------------+-------------+--------------+---------+
| virtual-machine | f1                                                               |             | block        | 1       |
+-----------------+------------------------------------------------------------------+-------------+--------------+---------+

stgraber@castiana:~$ lxc config device add f1 my-fs disk source=my-fs pool=default path=/srv/my-fs
Device my-fs added to f1
stgraber@castiana:~$ lxc config device add f1 my-block disk source=my-block pool=default
Device my-block added to f1

stgraber@castiana:~$ lxc start f1
stgraber@castiana:~$ lxc exec f1 bash
root@f1:~# gdisk -l /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_lxd_my-block
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: not present
  BSD: not present
  APM: not present
  GPT: not present

Creating new GPT entries in memory.
Disk /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_lxd_my-block: 20971520 sectors, 10.0 GiB
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): EA616112-9C49-4809-AA68-53895E752A34
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 20971486
Partitions will be aligned on 2048-sector boundaries
Total free space is 20971453 sectors (10.0 GiB)

Number  Start (sector)    End (sector)  Size       Code  Name
root@f1:~# df -h /srv/my-fs/
Filesystem      Size  Used Avail Use% Mounted on
lxd_my-fs        10G  128K   10G   1% /srv/my-fs
root@f1:~#