Long-term support (LTS) is a term used to describe special versions or editions of software designed to be supported for a longer than normal period. It is particularly applicable to open-source software projects.
It is a product lifecycle management policy for computer software, that applies the tenets of reliability engineering to the software development process and software release life cycle. Long-term support extends the period of software maintenance; it also alters the type and frequency of software updates (patches) to reduce the risk, expense, and disruption of software deployment, while promoting the dependability of the software. It does not, however, imply technical support.
At the beginning of a long-term support period, the software developers impose a feature freeze: They make patches to correct software bugs and vulnerabilities, but do not introduce new features that may cause regression. The software maintainer either distributes patches individually, or packages them in maintenance releases, point releases, or service packs. At the conclusion of the support period, the product reaches end-of-life.
The term long-term-support is usually reserved for special versions or editions of software that otherwise has a much shorter release life cycle. Typically, a publisher of LTS software maintains it for at least two years.
Need for long-term support
The traditional software lifecycle in many open source projects is release early, release often, or a regular time-based release schedule. In either case, each new release includes both fixes for security vulnerabilities and new functionality.
Large organisations, or users with mission critical projects, need the security fixes but would often prefer to retain the same base version for an extended period without any new or changed functionality. Their concern is, that as software developers add new features they can accidentally introduce new bugs or break old functionality. While in theory they could backport just the security fixes from each new release to their deployed version, in practise this would often be prohibitively difficult or costly.
Even without the added risks, for these types of users, new functionality is also often expensive. Updating a web application with a sensitive configuration, for example, may require the cooperation of many people: Developers for retrofitting; a database administrator for database schema changes; software testers for regression testing; a project manager for scheduling, liaising, and facilitating; a system administrator or release manager for software deployment oversight; and IT operations personnel for backups, installation, and disaster recovery.
LTS versions of a software package typically address these concerns by releasing only security-related updates for the LTS version - such that installing them should always be less risky than not installing them.
Software with separate LTS versions
This table only lists those have a specific LTS version in addition to a normal release cycle. Many projects, such as CentOS, provide a long period of support for every release.
|Software||Software type||Date of first LTS release||LTS period||STS period||Notes|
|Ubuntu||Linux distribution||1 June 2006
|5 years||9 months1||A new LTS version is released every two years. From 2006 through 2011, LTS support for the desktop was for approximately two years, and for servers five, but LTS versions are now supported for five years for both.|
|Trisquel 7.0 ||Linux distribution||2014-11-04||5 years||1 year||Linux Kernel-libre 3.13, GNOME fallback 3.12 or Sugar TOAST and Abrowser or GNU IceCat|
|Symfony||Application framework||June 2013||3 years||8 months|
|2 years, 3 months||7 months||Since Joomla! is a web application, long-term support also implies support for legacy web browsers.|
|Linux Mint||Linux distribution||8 June 2008||5 years||6 months||At version 13 the LTS period increased from three years to five, since Linux Mint derives from Ubuntu.|
|Linux kernel||Kernel||11 October 2008
|2–3 years||Varies||Linux kernel v2.6.16 and v2.6.27, were unofficially supported in LTS fashion before a 2011 working group in the Linux Foundation started a formal Long Term Support Initiative.|
|3 years (min.)||Varies||TYPO3 is a web application stewarded by the TYPO3 Association.|
|Mozilla Firefox||Web browser||31 January 2012
|1 year||6 weeks||Mozilla's LTS term is "Extended Support Release" (ESR) (see Firefox#Extended Support Release).|
- 1.^ The support period for Ubuntu's parent distribution, Debian, is one year after the release of the next stable version. For Debian 6.0 "Squeeze" there is an LTS project to provide security updates until February 2016. Decision on providing LTS for later releases is pending.
- "WHMCS Long-Term Support". WHMCS Documentation. WHMCS Ltd. Retrieved 28 June 2013.
- Brockmeier, Joe (1 June 2006). "Mark Shuttleworth on Ubuntu Long Term Support". Linux.com. Linux Foundation. Retrieved 20 June 2013.
- Darra, Clive et al. (23 May 2006 onward). "LTS". Ubuntu Wiki. Canonical Ltd. Retrieved 20 June 2013. Check date values in:
- Trisquel Belenos
- van Geest, M. et al. (22 August 2011 onward). "Release and support cycle". Joomla! Documentation. Joomla! Project Team. Retrieved 23 June 2013. Check date values in:
- "Linux Mint Releases". linuxmint.com. Retrieved 14 December 2013.
- Bunk, Adrian (11 October 2008). "Linux 2.6.27 will be a longtime supported kernel You use lambda expressions to create anonymous methods. Sometimes, however, a lambda expression does nothing but call an existing method. In those cases, it's often clearer to refer to the existing method by name. Method references enable you to do this; they are compact, easy-to-read lambda expressions for methods that already have a name.". Linux kernel (Mailing list). Retrieved 23 June 2013.
- Larabel, Michael (26 October 2011). "Linux Foundation Backs Long-Term Support Kernels". Phoronix. Phoronix Media. Retrieved 12 August 2013.
- "What is LTSI?". linuxfoundation.org. The Linux Foundation. Retrieved 12 August 2013.
- Baschny, Ernesto et al. (26 January 2011 onward). "TYPO3 4.5". TYPO3Wiki. TYPO3 Association. Retrieved 23 June 2013. Check date values in:
- Kern, Philipp; Piat, Franklin; Simmons, Geoff et al. (19 April 2006 onward). "Point Releases". Debian Wiki. Debian Project. Retrieved 27 June 2013. Check date values in:
- "Debian security FAQ". Debian.org. Debian Project. Retrieved 27 June 2013.
- "LTS - Debian Wiki". Debian Project. Retrieved 24 February 2015.
- Arnuphaptrairong, Tharwon (2011). "Top Ten Lists of Software Project Risks: Evidence from the Literature Survey" (PDF). Proceedings of the International MultiConference of Engineers and Computer Scientists 2011 1. ISBN 978-988-18210-3-4. ISSN 2078-0966. Retrieved 7 August 2013.
- "What makes software dependable?". bcs.org. BCS. 5 February 2007. Retrieved 12 August 2013.
- Brenner, Bill. "Outdated software is risky business". Search Security. TechTarget. Retrieved 12 August 2013.
- "Deploying software: Principles to ensure frequent, low-risk deployments". Government Service Design Manual. Government Digital Service. Retrieved 12 August 2013.
- Graydon, Patrick J.; Knight, John C.; Xiang Yin (2010). "Practical Limits on Software Dependability: A Case Study" (PDF). Retrieved 12 August 2013.
- Humble, Jez (16 February 2012). "Four Principles of Low-Risk Software Releases". InformIT. Pearson Education. Retrieved 12 August 2013.
- Littlewood, Bev; Strigini, Lorenzo. "Software Reliability and Dependability: A Roadmap" (PDF). Retrieved 12 August 2013.
- Weiss, Aaron (8 June 2012). "The Hidden Security Risks of Legacy Software". eSecurity Planet. Retrieved 12 August 2013.
- Ghosh, Shona (19 December 2013). "Windows XP: Microsoft’s ticking time bomb". PC Pro. Dennis Publishing. Retrieved 2 January 2014.