<story><title>The Broken Chain Problem</title><url>https://seekingquestions.blogspot.com/2017/03/four-parables-one-lesson-broken-chain.html</url></story><parent_chain></parent_chain><comment><author>jiggawatts</author><text>You see this in every field, including IT of course.&lt;p&gt;My favourite example of this was the introduction of the Microsoft Distributed File System (DFS) service into a customer environment. We were only using the DFS Namespaces feature, which is like DNS for file shares: the client downloads a blob of metadata and uses it to find an underlying file share for a logical name. The caching is very effective and the additional delay is negligible.&lt;p&gt;They had a file performance problem. So of course, they point the finger at the last thing that has changed in the environment: DFS! It must be DFS! I calmly point out that if the performance is bad &lt;i&gt;after&lt;/i&gt; a connection has been made, it can&amp;#x27;t possibly be DFS, it&amp;#x27;s out of path after the initial negotiation. It&amp;#x27;s like blaming DNS for slow downloads. Makes no sense! But nope. They just won&amp;#x27;t accept that. It&amp;#x27;s the last thing that has changed!&lt;p&gt;I came back a week later to discover that instead of 2 redundant DFS servers, there are now 6 redundant DFS servers &amp;quot;for performance&amp;quot;. To their surprise however, the file shares are still mysteriously behaving poorly.&lt;p&gt;They dragged me along to a meeting with a cast of thousands to discuss the issues. One guy spent most of the time arguing for increasing the number of DFS servers to 8, 10, or perhaps even more to solve the issue!&lt;p&gt;Meanwhile I&amp;#x27;m having a side-conversation with the storage guy, who sheepishly admits that 3 out of 4 fibre channel paths were down, and this started at about the same time frame as the deployment of DFS. I point this fact out to the room. Everyone looks at me while blinking slowly. A few more moments of silence pass. Then someone helpfully suggests adding more CPU and RAM to the DFS servers. Maybe 8 processors and 64 GB will do the trick!</text></comment>
<story><title>The Broken Chain Problem</title><url>https://seekingquestions.blogspot.com/2017/03/four-parables-one-lesson-broken-chain.html</url></story><parent_chain></parent_chain><comment><author>andi1304</author><text>&amp;quot;When you want to influence the world around you, make sure that your action is causally connected to whatever you want to influence.&amp;quot;&lt;p&gt;How can we know when an action is causally connected to an effect? Western philosophy since David Hume has struggled to find a solution to this problem. The &amp;#x27;problem of causality&amp;#x27;  is that it is extremely difficult to establish cause and effect with any degree of certainty. All we have is correlation. Modern thinkers (e.g. Judea Pearl) are still grappling with this problem today.&lt;p&gt;Pearl&amp;#x27;s fascinating talk on this subject at PyData 2018 is available on YouTube: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.youtube.com&amp;#x2F;watch?v=ZaPV1OSEpHw&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.youtube.com&amp;#x2F;watch?v=ZaPV1OSEpHw&lt;/a&gt;</text></comment>