Please note the following commands:
user@ubuntu:~$ sudo btrfs subvolume create /srv/audio
Create subvolume '/srv/audio'
user@ubuntu:~$ sudo btrfs fi show
Label: 'BTRFS_STORAGE' uuid: 0042d7c1-6850-42d2-9de8-3d408642b397
Total devices 3 FS bytes used 886.08GB
devid 1 size 931.51GB used 478.00GB path /dev/sdd
devid 3 size 1.82TB used 955.03GB path /dev/sde
devid 2 size 931.51GB used 477.03GB path /dev/sdc
Label: 'home' uuid: 5a869b17-5d30-462f-9abb-7095532a1994
Total devices 3 FS bytes used 3.70GB
devid 1 size 27.33GB used 0.00 path /dev/dm-1
devid 2 size 111.79GB used 5.03GB path /dev/sdb
devid 3 size 59.63GB used 1.03GB path /dev/sda
Btrfs v0.20-rc1
user@ubuntu:~$ sudo btrfs subvolume list /
ID 256 gen 17101 top level 5 path @
ID 258 gen 17064 top level 5 path @home
ID 261 gen 17079 top level 5 path @apt-snapshot-release-upgrade-saucy-2013-10-20_11:17:04
ID 269 gen 17100 top level 256 path srv/audio
user@ubuntu:~$
So, this is my first fresh installation with a btrfs root, ive used btrfs in the past with an ext4 root with mounted btrfs disks.
Its obvious that they are subvolumes of some sort, but I am unfamiliar with the "@" symbols in the pathname. What does it signify?