never change a running system

From the field of computing, likely from German never change a running system.

never change a running system

1. Do not change something while it is working (because there is a risk of breaking it).
   • 2007, Xing Zhou, Thomas Dreibholz, Erwin P. Rathgeb, “Improving the Load Balancing Performance of Reliable Server Pooling in Heterogeneous Capacity Environments”, in Serge Fdida, Kazunori Sugiura, editors, Sustainable Internet: Third Asian Internet Engineering Conference, AINTEC 2007 , →ISBN, page 126:

     That is, applying a specialised new policy to only improve a temporary capacity extension may be unsuitable (“Never change a running system!”).

   • 2012, Tiziana Margaria, Bernhard Steffen, “Service-Orientation: Conquering Complexity with XMDD”, in Mike Hinchey, Lorcan Coyle, editors, Conquering Complexity, →ISBN, page 224:

     This is the weakest point of the current practice: the deployment of complex systems on a heterogeneous, distributed platform is typically a nightmare, the required system-level testing is virtually unsupported, and maintenance and upgrading very often turn out to be extremely time consuming and expensive, de facto responsible for the slogan “never change a running system”.

   • 2019, Boris Scholl, Trent Swanson, Peter Jausovec, Cloud Native: Using Containers, Functions, and Data to Build Next-Generation Applications‎, →ISBN:

     “Never change a running system” is a widely used statement in software development, and it is also applicable when you consider moving your application to the cloud.

   • 2021, Andreas Graesser, Escape the Change Dilemma: Transformation to a Smart Data-Driven World‎, →ISBN:

     It’s not a coincidence that the following saying offers insight into the CIOs’ minds: ‘Never change a running system.’ However, just keeping the lights on seems to prevent innovation.

• This proverb is primarily used by non-native speakers of English.

• if it ain't broke, don't fix it
• leave well enough alone

Pseudo-anglicism, possibly from the field of computing, although this origin is disputed.^[1]

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never change a running system

1. if it ain't broke, don't fix it; leave well enough alone