2:1 is optimistic and generally only achievable for text data; a more realistic factor for a file system is 1.3:1 to 1.5:1, although drive compression applied to pre-compressed data can actually make the written data larger than having compression turned off in the tape drive. Media are guaranteed for 30 years of data retention under specified environmental conditions; they are easily damaged by mishandling (dropping or improper packaging during shipment.) Manufacturers of cartridges for the DLT/SDLT market are Fujifilm, Hitachi/Maxell and Imation. VStape is made by Sony. All other companies/brands (even Quantum) are contractors and/or resellers of these companies. A new naming convention took effect in 2005, calling the performance line DLT-S and the value line DLT-V. DLT includes Write Once Read Many (WORM) capability. In February 2007, Quantum stopped developing the next generations of DLT drives (S5 and V5) after insufficient market acceptance of the S4 and V4 drives, shifting its drive strategy to LTO. Generations Drives Media DLTtape IV can support both DLT4000/7000/8000 and DLT1/DLT-VS80 for full functions; once DLTtape IV media has been written to or formatted in a DLT7000/8000 drive, this media cannot be read, written to, or formatted in a DLT1/DLT-VS80 drive unless it is degaussed. Once the media has been written to or formatted in a DLT4000 drive, the media cannot be written to or formatted in a DLT1/DLT-VS80 drive unless it is degaussed but it can be read. This is because the DLT1/VS series use a different recording format that is not fully supported by the other family. Tapes written in value series drives can typically be read in (and often written to) higher end drives of a similar vintage, so long as the drive's technical specifications contain interoperability options. See also Symmetric Phase Recording References External links . DLT Roadmap (archived from 2006) at dlttape.com Obituary of Dr. Fred Hertrich, "father" of DLT Standards ECMA 197 Specification of DLT 2. ECMA 209 Specification of DLT 3. ECMA 231 Specification of DLT 4. ECMA 258 Specification of DLT 3-XT. ECMA 259 Specification of DLT 5. ECMA 286 Specification of DLT 6. ECMA 320 Specification of SDLT-1. DEC hardware Computer storage tape media Ecma standards