Short for drive letter access, DLA is a type of commercially available package that enables users to access optical storage media, CD or DVD, in a manner similar to how one uses a standard floppy disk.
Webopedia Quick Reference: Removable Storage Reference Accessing data from a disk is not as fast as accessing data from main memory, but disks are much cheaper. And unlike RAM, disks hold on to data even when the computer is turned off. Consequently, disks are the storage medium of choice for most types of data.