Digital Linear Tape (DLT) Basics

Updated 5/10/2011 by SuperMediaStore Staff

Digital Linear Tape (DLT) is a cartridge of magnetic tape that is typically used for long term computer data storage and backup. Magnetic tape on reels were used for data and program storage from the earliest days of computers, and in the form of DLT cartridges they remain a staple in many IT departments today.


The first generation of cartridge DLTs were introduced in the 1980s. Currently Quantum owns and licenses rights and produces the DLT drives, and its current version called SDLT. DLT became popular as a storage medium because cartridges were easy to use, handle, and store. Plus, the linear format allows multiple channels or tracks to be written simultaneously so large amounts of data can be saved or read quickly. In fact, its name comes from the how the tape is divided linearly into separate channels.


DLTs are still used today because of their reliability, their capacity, and the speed of data transfer. Frankly, they are also still in use because of the legacy tape drive devices already in place that still work and provide an economic and reliable method of long term data storage and back up.


Like most data storage technologies DLT capability has increased exponentially over time. When introduced, DLT had a storage capacity of 0.1 Gbytes with data transfer rates of about 0.05 Mbytes per second. Now DLTs can hold more than 800 Gbytes at 60 Mbytes per second. Coming generations are expected to hold a 3 to 6 Tbytes of data at data rates of more than 400 Mbytes per second.


With their stability when stored in proper conditions, their reliability during reuse, and their ever increasing capacity and capability, it is easy to see why IT professionals have stuck with using this tried and true storage media.