Once way to do that is to mount the shares that use the Greyhole storage pool, either on the HDA itself, or on a client computer on your local network, and copy your data from their existing location into the mounted shares.

This can be time consuming, but it is the safest way to use Greyhole.

Another way to move your files from their current location into the storage pool is to share their current location using an Amahi share that ''Uses pool'', then let Greyhole nightly check move the files from there into the pool.