Failed to format block device: Failed to run: mkfs.btrfs -L local

Sure, actually the issue comes from when adding storage to the cluster. Here is another error message.

root@pinehost1:~# lxc storage create local btrfs
Error: Failed to format block device: Failed to run: mkfs.btrfs -L local /dev/sda1: /dev/sda1 appears to contain an existing filesystem (btrfs).
ERROR: use the -f option to force overwrite of /dev/sda1
root@pinehost3:~# fdisk -l /dev/sda
Disk /dev/sda: 14.5 GiB, 15552479232 bytes, 30375936 sectors
Disk model: Ultra Fit       
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device     Boot Start      End  Sectors  Size Id Type
/dev/sda1        2048 30375935 30373888 14.5G 83 Linux
root@pinehost3:~# gdisk -l /dev/sda
GPT fdisk (gdisk) version 1.0.3

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


***************************************************************
Found invalid GPT and valid MBR; converting MBR to GPT format
in memory. 
***************************************************************


Warning! Secondary partition table overlaps the last partition by
33 blocks!
You will need to delete this partition or resize it in another utility.
Disk /dev/sda: 30375936 sectors, 14.5 GiB
Model: Ultra Fit       
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): C5E14FCA-448F-477E-809C-8142CC26209E
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 30375902
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048        30375935   14.5 GiB    8300  Linux filesystem
root@pinehost3:~# blkid /dev/sda
/dev/sda: PTTYPE="dos"