LTO – From Past to Present
Linear Tape-Open or more commonly referred to as LTO, is a magnetic tape data storage solution first created in the late 1990s as an open standards substitute to the proprietary magnetic tape formats that were available at the time. It didn’t take long for LTO tape to rule the super tape market and become the best-selling super tape format year after year. LTO is usually used with small and large computer systems, mainly for backup. The standard form-factor of LTO technology goes by the name Ultrium. The original version of LTO Ultrium was announced at the turn of the century and is capable of storing up to 100 GB of data in a cartridge. Miniscule in today’s standards, this was unheard of at the time. The most recent generation of LTO Ultrium is the eighth generation which was released in 2017. LTO 8 has storage capabilities of up 12 TB (30 TB at 2.5:1 compression rate).
The LTO Consortium is a group of companies that directs development and manages licensing and certification of the LTO media and mechanism manufacturers. The consortium consists of Hewlett Packard Enterprise, IBM, and Quantum. Although there are multiple vendors and tape manufacturers, they all must adhere to the standards defined by the LTO consortium.
LTO Consortium – Roadmap to the Future
The LTO consortium disclosed a future strategy to further develop the tape technology out to a 12th generation of LTO. This happened almost immediately after the release of the recent LTO-8 specifications and the LTO8 drives from IBM. Presumably sometime in the 2020s, when LTO-12 is readily available, a single tape cartridge should have capabilities of storing approximately half a petabyte of data.
According to the LTO roadmap, the blueprint calls for doubling the capacity of cartridges with every ensuing generation. This is the same model the group has followed since it distributed the first LTO-1 drives in 2000. However, the compression rate of 2.5:1 is not likely to change in the near future. In fact, the compression rate hasn’t increased since LTO-6 in 2013.
The Principles of How LTO Tape Works
LTO tape is made up of servo bands which act like guard rails for the read/write head. The bands provide compatibility and adjustment between different tape drives. The read/write head positions between two servo bands that surround the data band.
The read-write head writes multiple data tracks at once in a single, end-to-end pass called a wrap. At the end of the tape, the process continues as reverse pass and the head shifts to access the next wrap. This process is done from the edge to the center, known as linear serpentine recording.
More recent LTO generations have an auto speed mechanism built-in, unlike older LTO tape generations that suffered the stop-and-go of the drive upon the flow of data changes. The built-in auto speed mechanism lowers the streaming speed if the data flow, allowing the drive to continue writing at a constant speed. To ensure that the data just written on the tape is identical to what it should be, a verify-after-write process is used, using a read head that the tape passes after a write head.
But what about data security? To reach an exceptional level of data security, LTO has several mechanisms in place.
Due to several data reliability features including error-correcting code (ECC), LTO tape has an extremely low bit-error-rate that is lower than that of hard disks. With both LTO7 and LTO8 generations, the data reliability has a bit error rate (BER) of 1 x 10-19. This signifies that the drive and media will have one single bit error in approximately 10 exabytes (EB) of data being stored. In other words, more than 800,000 LTO-8 tapes can be written without error. Even more so, LTO tape allows for an air gap between tapes and the network. Having this physical gap between storage and any malware and attacks provides an unparalleled level of security.