Added a local check for already mounted volumes.
Fixes an issue when there are already mounted EBS volumes with the name /dev/xvd* (which is valid for HVM instances).
AWS does not throw an error if you attempt to attach /dev/sdf while /dev/xvdf is attached, although it resolves to the same device. Then attaching simple times out.
Added a local check for already mounted volumes. Fixes an issue when there are already mounted EBS volumes with the name /dev/xvd* (which is valid for HVM instances). AWS does not throw an error if you attempt to attach /dev/sdf while /dev/xvdf is attached, although it resolves to the same device. Then attaching simple times out.