Using your sonos to stream music from a NAS (network attached storage) drive can have its advantages as you don't need to keep a computer on all the time. Sonos makes it pretty easy but on OS X there's a small catch to the drive name. We'll walk through the process here:

Step 1) 

Select "Setup Music Library" from the Music tab in the Sonos Controller

Step 2)

Click Add to create a new library pointer

Step 3)

Locate the name of your NAS drive, it usually will appear in the SHARED category in any finder window. in our case our drive is named HIRO.

Step 4) 

Enter the path name to the drive and the 1st folder level of the NAS drive (don't go any deeper, sonos will find the music from there). In this case the path is simply //Hiro/Data.

NOTICE: The slashes go the opposite direction from the example. 

If your NAS requires a password or username enter it here as well.

Step 5) 

Let sonos index the music (usually takes minutes to hours depending on the size of your library). You'll now be able to stream all your music without having your computer running!