## 1.2.6 SuperDLT 

SuperDLT (SDLT) is a format specification that was developed by Quantum Corporation as an evolution of the DLT standard. It uses Laser Guided Magnetic Recording (LGMR) technology. This technology includes the Pivoting Optical Servo (POS). This optically assisted servo system is implemented on the unused reverse side of the media and uses a laser to read the servo guide. SDLT uses 100% of the media for data recording. SDLT uses Advanced Metal Powder (AMP) media, which contains embedded information for the Pivoting Optical Servo system. 

The recording mechanism is made of Magneto-Resistive Cluster (MRC) heads, which are a cluster of small magneto-resistive tape heads. 

The first SDLT drive (the SDLT 220) was introduced in late 2000. It provides a capacity of 110 GB (native) and 220 GB (with a 2:1 compression ratio). The native data transfer rate is 11 MBps. This first drive was not backward-read compatible with earlier models. In 2001, Quantum released a version of the SDLT 220 drive that was backward-read compatible with the DLTtape IV cartridge. 

The second SDLT 320 drive from Quantum became available in 2002. It increased the native capacity to 160 GB (320 GB with a 2:1 compression ratio) and the native transfer rate to 16 MBps (32 MBps with a 2:1 compression ratio). The SDLT 320 is backward read compatible with DLTtape IV cartridges and uses Super DLTtape I media. 

The SDLT 600 is the third generation of the SDLT product range from Quantum. It provides a capacity of 300 GB (native) and 600 GB (with a 2:1 compression ratio) and the native transfer rate increased to 36 MBps (72 MBps with a 2:1 compression ratio). The SDLT600 comes with an LVD 160 Small Computer System Interface (SCSI) or with a 2 GB Fibre Channel (FC) interface. The SDLT 600 is compatible with earlier versions with the SDLT 320 and the DLT VS 160. 

The DLT-S4 is the fourth generation of the SDLT product range from Quantum. It provides a capacity of 800 GB (native) and 1.6 TB (with a 2:1 compression ratio) and the native transfer rate increased to 324 MBps (400 MBps with a 2:1 compression ratio). The DLT-S4 comes with an LVD 320 Small Computer System Interface (SCSI) or with a 4 GB Fibre Channel (FC) interface. The DLT-S4 can read all Super DLTtape two cartridges that are written by SDLT 600 drives, and Super DLTtape 1 cartridges written by SDLT 320 drives. 

## 1.2.7 IBM 3850 

The media format has the following capacity: 

GLYPH<SM590000> DLT-4 (read/write) 800 GB native capacity 

GLYPH<SM590000> Super DLTtape II (read only) 300 GB native capacity 

GLYPH<SM590000> Super DLTtape I (read only) 160 GB native capacity 

Beginning in the late-1960s, IBM engineers in Boulder, Colorado, began development of a low-cost mass storage system that was based on magnetic tape in cartridges. By 1970, the proposed device was code named “Comanche” and was described as an online tape library to provide computer-controlled access to stored information. Numerous marketing studies and design changes were made during the early 1970s, and Comanche was announced as the IBM 3850 Mass Storage System (MSS) in October 1974. 

