#Check cache block of devices #Physical disk root@NAS:~# cat /sys/block/sda/queue/physical_block_size 512 #SSD disk root@NAS:~# cat /sys/block/sdb/queue/physical_block_size 4096 #Mechanical drive make-bcache -B --block 4096 /dev/sdb1 #SSD cache make-bcache -C --bucket 512 /dev/sda1 #Get the uuid of the cache device bcache-super-show /dev/sda1 | grep cset cset.uuid f0e01318-f4fd-4fab-abbb-d76d870503ec #Register cache device echo f0e01318-f4fd-4fab-abbb-d76d870503ec > /sys/block/bcache0/bcache/attach #Create the btrfs filesystem. mkfs.btrfs /dev/bcache0 #mount the filesystem mount /dev/bcache0 /mnt sudo mkdir -p /mnt/opennebula/{images,system,files}