Linear Tape-Open (LTO) is an open-format tape storage technology created by Hewlett-Packard (HP), International Business Machines (IBM) and Seagate Technology. The term open format means users have access to multiple sources of storage media products that will be compatible. The high-capacity, single-reel implementation of LTO technology is known as the LTO Ultrium format, or simply LTO Ultrium.
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HP, IBM and Seagate commenced work on the joint tape initiative in 1997, and they announced the LTO tape format specifications, technology roadmap and license availability the following year. Seagate’s tape business became Seagate Removable Storage Solutions in 2000, and the spin-off business took the name Certance in 2003. Quantum announced the purchase of Certance in 2004 and completed the acquisition in 2005. HP, IBM and Quantum continue to enhance LTO Ultrium and promote the LTO format.
The LTO Program requires that vendors licensing the technology pass annual third-party compliance verification tests. LTO Ultrium format-compliant products typically carry verification trademarks on tape drives and data cartridges.
Advancements in LTO technology have historically involved several factors, including the materials from which the tape is manufactured, the digital encoding and compression methods used, the physical speed with which the tape moves through the drive, the length of the tape in each cartridge, and the physical density of data bits on the tape. Additional capabilities added with subsequent generations include write-once, read-many (WORM), data encryption and partitioning to enable a linear tape file system (LTFS).
LTO generation roadmap
The LTO Ultrium technology has evolved through several generations since its introduction in 2000, and the LTO Ultrium roadmap provides the goals and objectives for future generations.
LTO-1: Generation 1 provided native capacity of up to 100 gigabytes (GB) and compressed capacity of up to 200 GB, assuming a compression ratio of 2:1. The maximum native data transfer rate was 20 megabytes per second (MBps), and the maximum compressed transfer rate was 40 MBps.
LTO-2: Generation 2 doubled the maximum storage capacity and data transfer rate over the prior LTO-1 generation. LTO-2 provided a maximum native capacity of 200 GB and a maximum compressed capacity of 400 GB. The maximum native data transfer rate was 40 MBps, and the maximum compressed transfer rate was 80 MBps. LTO-2 offered backward read-and-write capability with LTO-1 tape cartridges. Generation 2 products became available in 2003.
LTO-3: Generation 3 products became available in late 2004 and provided native data storage capacity of up to 400 GB and compressed capacity of up to 800 GB. The maximum native data transfer rate was 80 MBps, and the maximum compressed transfer rate was 160 MBps. LTO-3 added WORM capability to ensure data is not overwritten and to help address compliance regulations. Generation 3 offered backward-compatible read-and-write capability with LTO-2 cartridges and backward read capability with LTO-1 cartridges.
LTO-4: Generation 4 products reached the market in 2007 and provided a native storage capacity up to 800 GB and compressed capacity up to 1.6 terabytes (TB). The maximum native data transfer rate was 120 MBps, and the maximum compressed transfer rate was 240 MBps. Generation 4 added data encryption using the 256-bit Advanced Encryption Standard with the Galois/Counter Mode algorithm implemented at the drive level, enabling compression before encryption.
LTO-5: Generation 5 products became available in 2010 and offered a maximum native storage capacity of 1.5 TB and a maximum compressed capacity of 3 TB. The native data transfer rate was up to 140 MBps, and the compressed transfer rate was up to 280 MBps. Generation 5 added partitioning to enhance file control and space management via LTFS. One partition holds the file, and another partition is reserved for indexing to tell the drive where a file is stored in the tape.
LTO-6: Generation 6 became available in 2012 and provided a maximum native storage capacity of 2.5 TB and a maximum compressed capacity of 6.25 TB. Generation 6 is the first LTO generation for which the compressed capacity assumes a compression ratio of 2.5:1, through a larger compression history buffer. Generations 1 through 5 assumed a compression ratio of 2:1.
The native data transfer rate for Generation 6 is 160 MBps, and the compressed data rate is up to 400 MBps. LTO-6 supports previously added features such as WORM, hardware-based encryption, and partitioning, enabling LTFS. As with prior LTO generations, LTO-6 drives provide backward compatibility with the ability to read and write LTO-5 cartridges and read LTO-4 cartridges. An LTO Ultrium drive can read data from a cartridge in its own generation and two previous generations, and it can write data to a cartridge in its own generation and the immediate prior generation.
LTO-7: Expected to provide compressed capacity up to 16 TB and a compressed data transfer rate up to 788 MBps.
LTO-8: Expected to provide compressed capacity up to 32 TB and a compressed data transfer rate up to 1,180 MBps.
LTO-9: Expected to provide compressed capacity up to 62.5 TB and a compressed data transfer rate up to 1,770 MBps.
LTO-10: Expected to provide compressed capacity up to 120 TB and compressed data transfer rate up to 2,750 MBps.