Magnetic+Tape

** Magnetic Tape **

Magnetic tape was developed from magnetic wire in Germany by Fritz Pfleumer in 1928; it was originally intended for analogue audio recordings, so that radio programmes could be pre-recorded and edited, as before all radio broadcasts had to be live. Magnetic tape was soon used in the television industry for the same purpose, and was quickly adopted as a suitable medium for the distribution of video and audio.

On a Magnetic tape, data can only be written or read serially. This means that all of the data has to be kept together, which means you can’t skip to another piece of data. For example, On VHS, you can’t skip scene because the data has to be read in series.

Magnetic tape is written and read by passing the magnetic tape over a read or write head, that reads or writes information to the tape using electromagnetism. It was first used for data storage for computers in 1951 with the UNIVAC-1 designed by Eckert-Mauchly. The system used half-inch metallic tape with a storage density of 128 characters per inch, stored on 8 tracks. Modern tapes are based on a plastic tape with a magnetic coating.

IBM’s early floor standing tape drives used 10.5inch open tape reels that span intermittently and independently of each other, passing the tape through a U-shaped vacuum-column. These visually striking machines were used often in movies to represent ‘the-computer- in an era where computers were not commonplace.

Modern magnetic tape is a far smaller format, and is distributed in casettes, to facilitate easy handling and to protect the delicate tape. Modern tape formats include LTO, DLT and DAT. It remains in use due to its lower price:bit ratio resulting from a huge advantage over hard disks in recordable surface area, making it an inexpensive alternative to hard disks as a medium for backups where media removability is important. LTO3 tapes provide roughly 1GB for every £0.05 in cost.

** The Linear Tape Open Format **

Linear tape open or LTO is a popular tape format in use today, there have been several revisions since its introduction by the LTO consortium (consisting of IBM, HP and Seagate) LTO revision 5 or LTO5 was released in 2010.

LTO tapes are good for approximately 260 full file passes, that is, writing enough data to the drive to fill it completely. They can be stored for 15-30 years before falling apart and, should you feel that way inclined, they can be inserted and removed 5000 or so times.

**LTO Revision History** (bits/mm) ||= 4880 ||= 7398 ||= 9638 ||= 13250 ||= 15124 || <span style="font-family: Arial,Helvetica,sans-serif;">MB/S ||= <span style="font-family: Arial,Helvetica,sans-serif;">20 ||= <span style="font-family: Arial,Helvetica,sans-serif;">40 ||= <span style="font-family: Arial,Helvetica,sans-serif;">80 ||= <span style="font-family: Arial,Helvetica,sans-serif;">120 ||= <span style="font-family: Arial,Helvetica,sans-serif;">140 ||
 * = <span style="font-family: Arial,Helvetica,sans-serif;">Revision ||= <span style="font-family: Arial,Helvetica,sans-serif;">LTO1 ||= <span style="font-family: Arial,Helvetica,sans-serif;">LTO2 ||= <span style="font-family: Arial,Helvetica,sans-serif;">LTO3 ||= <span style="font-family: Arial,Helvetica,sans-serif;">LTO4 ||= <span style="font-family: Arial,Helvetica,sans-serif;">LTO5 ||
 * = <span style="font-family: Arial,Helvetica,sans-serif;">Capacity ||= <span style="font-family: Arial,Helvetica,sans-serif;">100GB ||= <span style="font-family: Arial,Helvetica,sans-serif;">200GB ||= <span style="font-family: Arial,Helvetica,sans-serif;">400GB ||= <span style="font-family: Arial,Helvetica,sans-serif;">800GB ||= <span style="font-family: Arial,Helvetica,sans-serif;">1.5TB ||
 * = <span style="font-family: Arial,Helvetica,sans-serif;">Total Tracks ||= <span style="font-family: Arial,Helvetica,sans-serif;">384 ||= <span style="font-family: Arial,Helvetica,sans-serif;">512 ||= <span style="font-family: Arial,Helvetica,sans-serif;">704 ||= <span style="font-family: Arial,Helvetica,sans-serif;">896 ||= <span style="font-family: Arial,Helvetica,sans-serif;">1280 ||
 * = <span style="font-family: Arial,Helvetica,sans-serif;">Linear Density
 * = <span style="font-family: Arial,Helvetica,sans-serif;">Data Transfer

<span style="font-family: Arial,Helvetica,sans-serif;">All LTO revisions are capable of 2:1 compression. The number of write elements doubled from 8 to 16 with LTO3, Filesystem encryption was introduced with LTO4 and the ability to partition a drive into 2 seperate recordable volumes with LTO5. Average seek time is 50 seconds, and total rewind time is a maximum of 80 seconds.

<span style="font-family: Arial,Helvetica,sans-serif;">A notable introduction with LTO3 is WORM, or Write Once Read Many, WORM tapes cannot be overwritten, this makes them useful for backups and legal recordkeeping, where data preservation is of high importance. Such tapes are two tone in colour; the standard manufacturers colour for the version of tape, with a light gray bottom plate.