Long-term support (LTS) is a product lifecycle management policy for computer software, especially open-source 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.
The need for long-term support
Deployment of LTS software is an optional strategy in IT risk management.
As software developers add new features and fix software bugs, they can accidentally introduce new bugs or break old functionality. To reduce the chance of software regression, the maintainers of LTS software only publish updates that either have low IT risk or that reduce IT risk. Patches for LTS software are published with the understanding that installing them is less risky than not installing them. Before deciding to apply a published update, an organisation might conduct a risk assessment.
For a large organisation or a mission critical project, deploying software updates can be not only risky, but 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.
The LTS policy prefers software quality over novel features. It assures administrators that they can rely on updates to the software for a specific period of time, and install updates with a reduced risk of regression.
Open-source software with long-term support
|Software||Software type||Date of first LTS release||LTS period||STS period||Notes|
|Fermi Linux||Linux distribution||26 January 2004||Varies||Varies||Fermi Linux is a derivative of Red Hat Enterprise Linux. It is maintained by Fermilab in concert with Scientific Linux.|
|Scientific Linux||Linux distribution||10 April 2004||Varies||N/A||All Scientific Linux releases have LTS. Scientific Linux is a derivative of Red Hat Enterprise Linux. It is a joint project of two particle physics laboratories: Fermilab and CERN. Support continues as long as Red Hat's support for upstream packages continues.|
|CentOS||Linux distribution||14 May 2004||10 years (approx.)||N/A||All CentOS releases have LTS. CentOS is a derivative of Red Hat Enterprise Linux.|
|Ubuntu||Linux distribution||1 June 2006
|5 years||6 months1||Canonical Ltd. decided to add LTS releases of their Linux distributions after introducing Ubuntu Server.
A new LTS version is released every 2 years. From 2006 through 2011, Ubuntu Desktop LTS had approximately 2 years of support, and Ubuntu Server LTS had 5. Starting with Ubuntu 12.04 LTS, both versions have 5 years of support.
|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. Only one LTS version is maintained at a time.|
|Linux kernel||Kernel||11 October 2008
|2–3 years||Varies||Two days after the gold master release of Linux kernel v2.6.27, Adrian Bunk volunteered to continue supporting it in LTS fashion, albeit for an uncertain amount of time. Bunk was the maintainer of Linux kernel v2.6.16, the previous "stable" (gold master) release. In 2011, a working group in the Linux Foundation started the Long Term Support Initiative, which standardized the LTS period.|
|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).|
|Eclipse||IDE||?||Varies||Varies||At the Eclipse Foundation, a working group defines the goals and prerequisites of long-term support for Eclipse software.|
- 1.^ The support period for Ubuntu's parent distribution, Debian, is one year, with a point release every two months.
- "WHMCS Long-Term Support". WHMCS Documentation. WHMCS Ltd. Retrieved 28 June 2013.
- "Fermi Linux Timeline". fermilinux.fnal.gov. Fermilab. Retrieved 18 January 2014.
- "Scientific Linux's Future". scientificlinux.org. Retrieved 18 January 2014.
- "Scientific Linux Distributions". scientificlinux.org. Retrieved 18 January 2014.
- 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.
- van Geest, M.; et al. (22 August 2011 onward). "Release and support cycle". Joomla! Documentation. Joomla! Project Team. Retrieved 23 June 2013.
- "Linux Mint Releases". linuxmint.com. Retrieved 14 December 2013.
- Bunk, Adrian (11 October 2008). "Linux 2.6.27 will be a longtime supported kernel". Linux kernel mailing list. http://marc.info/?l=linux-kernel&m=122375909403298. 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.
- "Eclipse Long Term Support Industry Working Group Charter". Eclipse.org. Eclipse Foundation. 12 June 2012. Retrieved 20 June 2013.
- Ross, Andrew; Daniel, Krzysztof; et al. (6 February 2012 onward). "LTS/LTS Ready". Eclipse Wiki. Eclipse Foundation. Retrieved 20 June 2013.
- Kern, Philipp; Piat, Franklin; Simmons, Geoff; et al. (19 April 2006 onward). "Point Releases". Debian Wiki. Debian Project. Retrieved 27 June 2013.
- "Debian security FAQ". Debian.org. Debian Project. Retrieved 27 June 2013.
- 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.