Comment 6 for bug 1555700

Linking against libaio allows tgt to use libaio as a backend for submitting IO to the backing device.
The default backend uses pread64/pwrite64. Adding an additional backed does not change this default

For users to consume the aio backend, they must specify the backend type via command line switch (from tgtadm manpage):

-E, --bstype <type>
           When creating a LUN, this parameter specifies the type of backend
           storage to to use.

I believe that aio is out of the way for default users. I'd like to get some testing done on the aio backend before we say we'll support it.