computer science

Long-term support

Long-term support is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Long-term support rather than just read about it. In short: Long-term support (LTS) is a product lifecycle management policy in which a stable release of computer software is maintained for a longer period of time than the standard edition. The term is typically reserved for open-source software, where it describes a software edition that is supported for months or years longer than the software's standard edition.

Key takeaways

Long-term support belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Long-term support to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Long-term support from memory before moving on to harder problems.

Reference excerpt

Long-term support (LTS) is a product lifecycle management policy in which a stable release of computer software is maintained for a longer period of time than the standard edition. The term is typically reserved for open-source software, where it describes a software edition that is supported for months or years longer than the software's standard edition. This is often called an extended-support release. Short-term support (STS) is a term that distinguishes the support policy for the software's standard edition. STS software has a comparatively short life cycle, and may be afforded new features that are omitted from the LTS edition to avoid potentially compromising the stability or compatibility of the LTS release.

Characteristics LTS 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 prioritizing the dependability of the software. It does not necessarily 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 either reaches end-of-life, or receives a reduced level of support for a period of time (e.g., high-priority security patches only).

Rationale

Before upgrading software, a decision-maker might consider the risk and cost of the upgrade. As software developers add new features and fix software bugs, they may introduce new bugs or break old functionality. When such a flaw occurs in software, it is called a regression. Two ways that a software publisher or maintainer can reduce the risk of regression are to release major updates less frequently, and to allow users to test an alternate, updated version of the software. LTS software applies these two risk-reduction strategies. The LTS edition of the software is published in parallel with the STS (short-term support) edition. Since major updates to the STS edition are published more frequently, it offers LTS users a preview of changes that might be incorporated into the LTS edition when those changes are judged to be of sufficient quality. While using older versions of software may avoid the risks associated with upgrading, it may introduce the risk of losing support for the old software. Long-term support addresses this by assuring users and administrators that the software will be maintained for a specific period of time, and that updates selected for publication will carry a significantly reduced risk of regression. The maintainers of LTS software only publish updates that either have low IT risk or that reduce IT risk (such as security patches). Patches for LTS software are published with the understanding that installing them is less risky than not installing them.

Software with separate LTS versions This table only lists software that 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.

1.^ The support period for Ubuntu's parent distribution, Debian, is one year after the release of the next stable version. Since Debian 6.0 "Squeeze", LTS support (bug fixes and security patches) was added to all version releases. The total LTS support time is generally around 5 years for every version. Due to the irregular release cycle of Debian, support times might vary from that average and the LTS support is done not by the Debian team but by a separate group of volunteers.

Worked examples

Example 1 — a first encounter with Long-term support

Start with the simplest possible case. Write down what Long-term support claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Long-term support before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Long-term support ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Long-term support

In research: Long-term support appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Long-term support in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Long-term support is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer security procedures, Product lifecycle management, Reliability engineering, so understanding it makes those chapters shorter.
In everyday life: Look for Long-term support outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Long-term support in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Long-term support means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Long-term support out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Long-term support in simple terms?

Why does Long-term support matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Long-term support?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Long-term support.