Abandoning Scientific Linux Was a Mistake
Abandoning Scientific Linux Was a Mistake
放弃 Scientific Linux 是一个错误
A recent CERN announcement caught my attention. By the end of 2026, more than 2,200 industrial computers and embedded systems around CERN’s accelerator complex are expected to be running Debian 13. CERN is not abandoning the Red Hat ecosystem. AlmaLinux and RHEL remain the main supported Linux distributions across much of the organization; Debian support is currently limited to accelerator front-end systems. Still, the move took me back to a decision made more than a decade ago: CERN and Fermilab’s gradual abandonment of Scientific Linux. With hindsight, I think it was a mistake. Not because Scientific Linux was technically superior to CentOS, or because maintaining another Linux distribution was free. And not because CERN or Fermilab could somehow have controlled what Red Hat or IBM later chose to do. The mistake was treating Scientific Linux mainly as duplicated engineering work. It was infrastructure.
最近 CERN 的一则公告引起了我的注意。预计到 2026 年底，CERN 加速器综合体周围将有超过 2,200 台工业计算机和嵌入式系统运行 Debian 13。CERN 并没有放弃 Red Hat 生态系统。AlmaLinux 和 RHEL 仍然是该组织大部分地区主要支持的 Linux 发行版；Debian 的支持目前仅限于加速器前端系统。尽管如此，这一举动还是让我回想起十多年前做出的一个决定：CERN 和费米实验室（Fermilab）逐渐放弃 Scientific Linux。事后看来，我认为这是一个错误。并不是因为 Scientific Linux 在技术上优于 CentOS，也不是因为维护另一个 Linux 发行版是免费的。更不是因为 CERN 或费米实验室能够以某种方式控制 Red Hat 或 IBM 后来选择做什么。错误在于将 Scientific Linux 主要视为重复的工程工作，而它实际上是基础设施。
What Scientific Linux was solving
Scientific Linux 解决了什么问题
Scientific Linux grew out of a practical problem in High Energy Physics. Large experiments span laboratories, universities, computing centers, and countries. If one site builds against one version of glibc, another uses something slightly different, and a third runs an entirely different packaging environment, things become painful very quickly. The scientific community also needed an unusual combination: a Linux distribution that would remain stable for years, work with enterprise software, be freely redistributable, and run across institutions without requiring a commercial license for every machine. Red Hat Enterprise Linux provided the stability and long lifecycle, and Red Hat published the source needed to rebuild it. Scientific Linux turned that source into a community resource. Fermilab announced the distribution in 2003, and CERN joined soon afterward. It eventually spread far beyond those two laboratories. Universities, research institutions, experiments, companies, and even systems aboard the International Space Station used it or distributions derived from it. Scientific Linux was never simply “RHEL with a different wallpaper.” It gave the scientific community an institutionally independent implementation of the Enterprise Linux platform.
Scientific Linux 源于高能物理领域的一个实际问题。大型实验跨越了实验室、大学、计算中心和多个国家。如果一个站点基于某个版本的 glibc 进行构建，另一个站点使用略有不同的版本，而第三个站点运行完全不同的打包环境，那么事情很快就会变得非常棘手。科学界还需要一种不同寻常的组合：一个能够保持多年稳定、能与企业软件兼容、可自由重新分发，并且无需为每台机器购买商业许可即可在各机构间运行的 Linux 发行版。Red Hat Enterprise Linux 提供了稳定性和长生命周期，而 Red Hat 发布了重建它所需的源代码。Scientific Linux 将这些源代码转化为一种社区资源。费米实验室于 2003 年宣布了该发行版，CERN 随后不久也加入了进来。它最终传播到了这两个实验室之外。大学、研究机构、实验项目、公司，甚至国际空间站上的系统都使用它或其衍生版本。Scientific Linux 从来不仅仅是“换了壁纸的 RHEL”。它为科学界提供了一个机构独立的 Enterprise Linux 平台实现。
Then CentOS looked like the obvious answer
当时 CentOS 看起来是显而易见的答案
When Red Hat and CentOS joined forces in 2014, moving to CentOS looked perfectly reasonable. CentOS already offered what many Scientific Linux users wanted: a freely available Enterprise Linux rebuild backed by a much larger general-purpose community. CERN began moving its next major release from Scientific Linux CERN to CERN CentOS 7. Scientific Linux 5 and 6 remained supported, but the future platform at CERN would be based on CentOS. The rationale was compelling. Why should CERN and Fermilab spend scarce engineering time rebuilding a Linux distribution when CentOS was already doing essentially the same work? Why maintain an HEP-specific distribution when the scientific community could converge on a larger common platform? If Red Hat itself was supporting the CentOS project, that seemed to make the platform more sustainable, not less. In 2019, Fermilab took the argument to its logical conclusion or its literal “end.” There would be no Scientific Linux 8. Fermilab would deploy CentOS 8 instead and work with CERN and other laboratories to improve CentOS for high-energy physics. Taken on its own, this was not an irrational decision. But it removed something that was hard to see on a spreadsheet: a credible exit.
当 Red Hat 和 CentOS 在 2014 年联手时，转向 CentOS 看起来非常合理。CentOS 已经提供了许多 Scientific Linux 用户想要的东西：一个由更庞大的通用社区支持的、可免费获取的 Enterprise Linux 重建版。CERN 开始将其下一个主要版本从 Scientific Linux CERN 迁移到 CERN CentOS 7。Scientific Linux 5 和 6 仍然得到支持，但 CERN 未来的平台将基于 CentOS。这一理由很有说服力。既然 CentOS 已经在做本质上相同的工作，为什么 CERN 和费米实验室还要花费宝贵的工程时间去重建一个 Linux 发行版呢？当科学界可以汇聚到一个更大的通用平台时，为什么要维护一个 HEP（高能物理）专用的发行版呢？如果 Red Hat 本身就在支持 CentOS 项目，这似乎只会让该平台更具可持续性，而不是相反。2019 年，费米实验室将这一论点推向了逻辑上的结论，或者说是字面意义上的“终点”。将不会有 Scientific Linux 8。费米实验室将改用 CentOS 8，并与 CERN 及其他实验室合作，为高能物理改进 CentOS。单独来看，这并不是一个不理性的决定。但它移除了一样在电子表格上难以体现的东西：一个可靠的退出机制。
A distribution has option value
发行版具有期权价值
This is what I think we underestimated. The cost of maintaining Scientific Linux was visible. People had to rebuild packages, test updates, maintain repositories, produce releases, handle security updates, and support users. The benefit of an independent distribution was harder to quantify. As long as CentOS behaved exactly as CERN and Fermilab expected, Scientific Linux looked redundant. That is how redundancy always looks when nothing has failed yet. Scientific Linux gave the scientific community its own implementation of a RHEL-compatible computing environment. More importantly, it kept alive the people, processes, infrastructure, and institutional knowledge needed to maintain one. That capability had option value. You might not need to exercise the option this year, or even this decade. It becomes valuable when the assumptions underneath your primary platform change. Those assumptions changed surprisingly quickly.
我认为我们低估了这一点。维护 Scientific Linux 的成本是显而易见的。人们必须重建软件包、测试更新、维护存储库、发布版本、处理安全更新并支持用户。而一个独立发行版的好处则难以量化。只要 CentOS 的表现完全符合 CERN 和费米实验室的预期，Scientific Linux 看起来就是多余的。当一切尚未出问题时，冗余总是看起来如此。Scientific Linux 为科学界提供了属于他们自己的 RHEL 兼容计算环境实现。更重要的是，它保留了维护这样一个环境所需的人员、流程、基础设施和机构知识。这种能力具有“期权价值”。你可能今年甚至这十年都不需要行使这个期权。但当你的主要平台底层的假设发生变化时，它就变得非常有价值。而这些假设的变化速度快得惊人。
[!NOTE] CERN uses a similar argument to justify the FCC: the knowledge required to build large machines such as accelerators and detectors is valuable and must be preserved. If Europe does not build the next machine after the LHC, that expertise may be lost, the next large machine may be built in China, and Europe may lose its technological leadership in the field. The same argument applies to software infrastructure.
[!NOTE] CERN 使用类似的论点来证明 FCC（未来环形对撞机）的合理性：建造加速器和探测器等大型机器所需的知识是宝贵的，必须予以保留。如果欧洲不在 LHC 之后建造下一台机器，那么这些专业知识可能会流失，下一台大型机器可能会在中国建造，而欧洲可能会失去在该领域的技术领先地位。同样的论点也适用于软件基础设施。
The CentOS assumption did not last
CentOS 的假设并未持续太久
In December 2020, Red Hat changed the role of CentOS. CentOS Linux, the traditional downstream rebuild of released RHEL versions was discontinued in favor of CentOS Stream, which sits ahead of RHEL rather than behind it. This was more than a change in release cadence. Organizations had standardized on CentOS because they wanted a freely distributable approximation of the current RHEL release. The product they had standardized on effectively ceased to exist. CERN and Fermilab immediately had to reconsider their Linux strategy. CERN noted that the shorter CentOS Stream lifecycle was incompatible with some scientific use cases. The laboratories evaluated Stream, RHEL licensing arrangements, and the emerging Enterprise Linux rebuilds. By 2022, CERN and Fermilab were recommending AlmaLinux as the standard distribution for experiments. The circularity is hard to miss. Scientific Linux had been retired partly because maintaining another RHEL rebuild seemed unnecessary while CentOS existed. A few years later, the community needed an independent RHEL-compatible distribution again.
2020 年 12 月，Red Hat 改变了 CentOS 的角色。传统的、作为已发布 RHEL 版本下游重建版的 CentOS Linux 被终止，取而代之的是 CentOS Stream，它位于 RHEL 之前而非之后。这不仅仅是发布节奏的改变。各组织之所以标准化使用 CentOS，是因为他们想要一个可自由分发的、当前 RHEL 版本的近似物。他们所标准化的产品实际上已不复存在。CERN 和费米实验室不得不立即重新考虑他们的 Linux 策略。CERN 指出，CentOS Stream 较短的生命周期与某些科学用例不兼容。这些实验室评估了 Stream、RHEL 的许可安排以及新兴的 Enterprise Linux 重建版。到 2022 年，CERN 和费米实验室已建议将 AlmaLinux 作为实验的标准发行版。这种循环往复显而易见。Scientific Linux 之所以被淘汰，部分原因是当 CentOS 存在时，维护另一个 RHEL 重建版似乎没有必要。几年后，社区又再次需要一个独立的 RHEL 兼容发行版了。