In an earlier post I mentioned that prior to the introduction of LTFS an application typically relied on proprietary APIs to read and write data tape. These proprietary APIs typically have used proprietary data formats on the tape media. These proprietary APIs and data formats lock an application developer to a specific layer of software which mediates access to the data tape storage.
With LTFS we took a very different approach. The LTFS filesystem-based approach to accessing data stored on tape brings significant benefits to the tape market. For example, application developers no longer need to learn specialized APIs, and users get a fully self-describing storage medium that largely behaves the same as more common storage media such as hard-disk drives and memory sticks.
The benefits afforded by LTFS are arguably sufficient to support releasing LTFS as proprietary software that uses a closed data format on the tape media. Rather than treating LTFS as yet another proprietary on-tape format, the LTFS team at IBM elected to release the LTFS Single Drive Edition (LTFS-SDE) software as open-source. The LTFS open-source software release is licensed under the LGPL license to protect the LTFS format while providing application developers the ability to dynamically link with LTFS binary code without risking their own intellectual property. Each fix-pack released for LTFS-SDE has also been released under the LGPL.
In addition to the open-source software release, the LTFS team wrote the LTFS Format Specification document and released this specification to the public. This Format Specification describes the on-media data structures in sufficient detail for independent developers to read and write LTFS tapes that are compatible with other LTFS implementations.
During development of the LTFS software and the LTFS Format Specification the IBM team built a working relationship with developers at both HP and Quantum through the LTO Consortium. These relationships afforded an opportunity to inform HP and Quantum about the up-coming LTFS technology and allowed for some pre-release co-ordination between these three LTO 5 vendors. These on-going relationships have provided the opportunity to conduct inter-operablity testing between all three vendors. We are fortunate to enjoy continuing discussions between vendors on the direction and development of the LTFS format.
This communication, the open-specification, and the open-source approach to software distribution is motivated by a desire for LTFS to become an industry-wide standard. During LTFS development we recognized that if LTFS was a proprietary release then we would be adding to the fragmentation and incompatibility of data tape use. Instead, a release of LTFS as an open implementation with an open specification would create an environment that may lead to broad industry adoption. Broad adoption along with the ease of use benefits may result in expanded use of tape media for data storage. Expansion of the tape market would be good for the industry and all of us involved in the data tape business.
