<story><title>On the strange joys of mainframe OSes that have survived into modern times</title><url>https://liam-on-linux.dreamwidth.org/86995.html</url></story><parent_chain><item><author>jasode</author><text>&lt;i&gt;&amp;gt;I read this wonderful article on mainframe OSes.&lt;/i&gt;&lt;p&gt;As irony, the url link points to an article mentioning the Unisys mainframe. Unisys later switched to running on commodity x86 servers with a Unisys emulation on top:  &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=unisys+clearpath+shift+xeon&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=unisys+clearpath+shift+xeon&lt;/a&gt;&lt;p&gt;&lt;i&gt;&amp;gt;, and that you don’t need all the fancy scaling infrastructure because one modern box [mainframe] can support a million concurrent users no problem, and a few such boxes can support tens of hundreds of millions of them, all in something in the corner of one room, with an uptime of decades and no need for any cloud.  But it’s hard to do it that way, &lt;/i&gt;&lt;p&gt;The author proposes that &amp;quot;mainframes-are-superior&amp;quot; by vague generalizations and no performance data.&lt;p&gt;As a case study, consider that the Sabre travel reservations was the &lt;i&gt;first IBM mainframe commercial customer&lt;/i&gt; since 1960.  With 6 decades of experience with IBM 360 and Z upgrades, they&amp;#x27;d know more about running mission-critical performance workloads on mainframes than just about anyone.&lt;p&gt;And yet, they&amp;#x27;ve been &lt;i&gt;migrating off of mainframes&lt;/i&gt; to AWS + Azure + Google cloud : &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=sabre+migration+multi-cloud+google&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=sabre+migration+multi-cloud+...&lt;/a&gt;&lt;p&gt;To think of the opposite case from Sabre, let&amp;#x27;s consider a new YC startup today with no legacy IT systems.  Thinking from first principles (i.e. raw math of cpu &amp;amp; io performance &amp;amp; costs on an Excel spreadsheet), what situation makes sense to build the solution on an a new IBM z16 mainframe instead of cloud?&lt;p&gt;If one is an old bank already running an older IBM z14 or z15 mainframe and wants the next iteration of performance improvements, a z16 upgrade is the simplest so probably makes the most financial sense.  But without a &amp;quot;legacy IT&amp;quot; constraint, what&amp;#x27;s the compelling spreadsheet model for a YC company to choose a mainframe?</text></item></parent_chain><comment><author>derefr</author><text>&amp;gt; raw math of cpu &amp;amp; io performance &amp;amp; costs on an Excel spreadsheet&lt;p&gt;But that&amp;#x27;s not the raw math; the raw math is &amp;quot;total OpEx&amp;quot;, and OpEx for these large systems is increasingly dominated not by the systems themselves, but rather by development-talent acquisition costs, and operational-maintenance talent labor costs.&lt;p&gt;Even Sabre&amp;#x27;s choice wasn&amp;#x27;t &amp;quot;upgrade to z16 vs. move to IaaS&amp;quot;; it was &amp;quot;hire people to replace churned devs+ops to write the next feature of the system: people with z&amp;#x2F;OS experience, or people with IaaS experience?&amp;quot;</text></comment>
<story><title>On the strange joys of mainframe OSes that have survived into modern times</title><url>https://liam-on-linux.dreamwidth.org/86995.html</url></story><parent_chain><item><author>jasode</author><text>&lt;i&gt;&amp;gt;I read this wonderful article on mainframe OSes.&lt;/i&gt;&lt;p&gt;As irony, the url link points to an article mentioning the Unisys mainframe. Unisys later switched to running on commodity x86 servers with a Unisys emulation on top:  &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=unisys+clearpath+shift+xeon&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=unisys+clearpath+shift+xeon&lt;/a&gt;&lt;p&gt;&lt;i&gt;&amp;gt;, and that you don’t need all the fancy scaling infrastructure because one modern box [mainframe] can support a million concurrent users no problem, and a few such boxes can support tens of hundreds of millions of them, all in something in the corner of one room, with an uptime of decades and no need for any cloud.  But it’s hard to do it that way, &lt;/i&gt;&lt;p&gt;The author proposes that &amp;quot;mainframes-are-superior&amp;quot; by vague generalizations and no performance data.&lt;p&gt;As a case study, consider that the Sabre travel reservations was the &lt;i&gt;first IBM mainframe commercial customer&lt;/i&gt; since 1960.  With 6 decades of experience with IBM 360 and Z upgrades, they&amp;#x27;d know more about running mission-critical performance workloads on mainframes than just about anyone.&lt;p&gt;And yet, they&amp;#x27;ve been &lt;i&gt;migrating off of mainframes&lt;/i&gt; to AWS + Azure + Google cloud : &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=sabre+migration+multi-cloud+google&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.google.com&amp;#x2F;search?q=sabre+migration+multi-cloud+...&lt;/a&gt;&lt;p&gt;To think of the opposite case from Sabre, let&amp;#x27;s consider a new YC startup today with no legacy IT systems.  Thinking from first principles (i.e. raw math of cpu &amp;amp; io performance &amp;amp; costs on an Excel spreadsheet), what situation makes sense to build the solution on an a new IBM z16 mainframe instead of cloud?&lt;p&gt;If one is an old bank already running an older IBM z14 or z15 mainframe and wants the next iteration of performance improvements, a z16 upgrade is the simplest so probably makes the most financial sense.  But without a &amp;quot;legacy IT&amp;quot; constraint, what&amp;#x27;s the compelling spreadsheet model for a YC company to choose a mainframe?</text></item></parent_chain><comment><author>neverartful</author><text>&amp;quot;But without a &amp;quot;legacy IT&amp;quot; constraint, what&amp;#x27;s the compelling spreadsheet model for a YC company to choose a mainframe?&amp;quot;&lt;p&gt;The most compelling reasons for the mainframe, based on its intrinsic values, are &amp;#x27;RAS&amp;#x27; (reliability, availability, serviceability). However, those virtues come with a very high price tag. So far the most part, I cannot imagine any startup business choosing one (UNLESS system downtime will kill the business).</text></comment>