I launched an EBS backed AMI with all the defaults.

I noticed that it automicatlly had attached an ephemeral disk.

I was just wondering if there was a good programtic way to know that this particular device is ephemeral vs some EBS volume I had decided to attach:

ubuntu@-----:~$ df -ahT
Filesystem     Type        Size  Used Avail Use% Mounted on
/dev/xvda1     ext4        7.9G  867M  6.7G  12% /
proc           proc           0     0     0    - /proc
sysfs          sysfs          0     0     0    - /sys
none           fusectl        0     0     0    - /sys/fs/fuse/connections
none           debugfs        0     0     0    - /sys/kernel/debug
none           securityfs     0     0     0    - /sys/kernel/security
udev           devtmpfs    1.9G   12K  1.9G   1% /dev
devpts         devpts         0     0     0    - /dev/pts
tmpfs          tmpfs       751M  172K  750M   1% /run
none           tmpfs       5.0M     0  5.0M   0% /run/lock
none           tmpfs       1.9G     0  1.9G   0% /run/shm
/dev/xvdb      ext3        394G  199M  374G   1% /mnt

ubuntu@-----:~$ mount
/dev/xvda1 on / type ext4 (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
/dev/xvdb on /mnt type ext3 (rw,_netdev)