OK, with my limited linux knowledge and with a little help from a friend I can say :
First, scrub didn’t work. And I cannot run the command btrfs check –repair because,
there’s no partition on my data disks (/dev/sda, /dev/sdb, … , /dev/sdf)
ex : btrfs check –repair /dev/sda1, btrfs check –repair /dev/sda.
And when I run the fdisk /dev/sda command, there’s another error message about the btrfs.
Any more suggestions?