Also known as: LTO Ultrium, Ultrium
The open tape cartridge standard used by IBM's tape libraries and autoloaders, currently on its 10th generation (LTO-10, 40 TB native per cartridge).
LTO, short for Linear Tape-Open, is the open (multi-vendor) magnetic tape standard behind essentially every enterprise tape library sold today, including IBM's TS4300, TS4500, and TS2900 lines. It was developed jointly by IBM, HPE, and Quantum specifically so tape media and drives from different manufacturers stay interoperable, unlike the closed, single-vendor tape formats it replaced.
Each LTO generation roughly doubles native cartridge capacity over the last. As of 2026 the current generation is LTO-10, at 40 TB native (up to 100 TB at 2.5:1 compression) per cartridge and 400 MBps native transfer speed. LTO-9, the prior generation, holds 18 TB native.
Media compatibility changes by generation. LTO 1 through 7 retain the older read/write pattern; LTO 8 reads and writes LTO 7 and 8, and LTO 9 reads and writes LTO 8 and 9. LTO 10 reads and writes LTO 10 only. Compare read and write compatibility before replacing a drive that must restore older cartridges.
Cartridge capacity and the drive interface answer different questions. Understand native and compressed tape capacity and match the drive connection and assembly format before requesting a configuration quote.