Data is the lifeblood of modern organisations, and it keeps growing. Finding storage that is efficient, affordable and safe for the long term is a priority for every IT team. Linear Tape-Open (LTO) technology has become the standard answer for backup and archive at scale. This guide explains what LTO is, how it works and why it matters.
What is LTO?
LTO (Linear Tape-Open) is an open-standard magnetic tape technology. It was created in the late 1990s by HP, IBM and Seagate, and today it is governed by the LTO Program, whose technology provider companies are HPE, IBM and Quantum. “Open” means the specification is licensed to several manufacturers. Drives and cartridges from different brands are interchangeable within a generation, and no single company controls the format.
The data cartridges are called LTO Ultrium. Each generation is numbered (LTO-1, LTO-2 and so on up to LTO-10), with capacity rising from 100GB in 2000 to 40TB today.
How LTO works
An LTO cartridge contains a single reel of half-inch (12.65mm) magnetic tape, up to about a kilometre long. When the cartridge is loaded, the drive threads the tape past its read/write head and onto a take-up reel inside the drive.
- Serpentine recording: data is written in bands of parallel tracks as the tape runs end to end. The head then steps across and writes the next set on the return pass. Modern cartridges hold thousands of tracks.
- Servo tracks written at the factory keep the head precisely aligned with the data.
- Read-after-write verification: the drive reads data back immediately after writing it and rewrites any block that fails.
- Cartridge memory: a small chip stores the tape’s usage history and index information, so it loads faster.
Capacity and performance
The latest LTO-10 generation stores 30TB native on the standard cartridge and 40TB native on the extended cartridge. With 2.5:1 compression, that becomes 75TB and 100TB. Drives stream data at up to 400MB/s native, which keeps backup windows short and makes restores of large data sets fast. See the capacity chart for every generation.
Compatibility
LTO drives have traditionally supported older cartridges, so organisations can upgrade without losing access to data. Up to LTO-7, drives read two generations back and wrote one back. LTO-8 and LTO-9 support one generation back, and LTO-10 supports only LTO-10. Planning migrations is part of managing a long-term tape archive. See our compatibility guide.
Data encryption
Since LTO-4, every drive includes hardware AES-256 encryption. Data is encrypted at the drive at full speed, so tapes can be stored offsite or shipped without the risk of exposing sensitive information. Encryption keys are managed by the backup application, the library or an external key manager.
Data life
LTO media is rated for up to 30 years of archive life when stored correctly (16–25°C, 20–50% RH). The cartridge is physically robust, and tape is not affected by the kind of mechanical or electronic failure that can destroy a hard drive. The practical limit is usually how long compatible drives remain available, not the tape itself.
Scaling up
LTO scales from a single tape drive to autoloaders and huge tape libraries holding thousands of cartridges and exabytes of data. Adding capacity means adding cartridges, with no new infrastructure required. That is why the world’s largest cloud providers use LTO-based libraries for their deep archive tiers.
Beyond backup: LTFS
Since LTO-5, the Linear Tape File System has let a cartridge be mounted and used like a disk, with drag and drop in your normal file manager. This turned LTO into a universal medium for exchanging and archiving large files, especially in media and research.
Conclusion
LTO combines high capacity, fast streaming, strong security, long life and an open, multi-vendor ecosystem. For backup copies and long-term archives, nothing else offers the same balance of cost and resilience. See the benefits of LTO, or talk to us about putting it to work.