From: g4ugm@dave.invalid   
      
   On 16/09/2025 22:49, Lawrence D’Oliveiro wrote:   
   > On Tue, 16 Sep 2025 21:47:08 +0100, David Wade wrote:   
   >   
   >>> Especially given that z/OS is actually several years older than VMS   
   >>> and is still going very strongly indeed.   
   >>>   
   >> I don't believe its as strong as you believe. Perhaps the Z platform   
   >> is, but z/OS is pretty much limited to traditional big banks and   
   >> airline reservation systems. These systems are all much larger that   
   >> most VMS systems so migration away is harder and riskier. The   
   >> hundreds of SMEs that once had a small IBM/370 like the 43xx or 9370   
   >> have gone.   
   >   
   > IBM as a whole has been losing money for years, and laying off staff   
   > left and right. That’s not exactly the sign of a platform “going   
   > strongly”, is it. The only recent bright spot in the company, that I   
   > know of, is its Red Hat acquisition.   
   >   
      
   Why hasn't it gone bust? Its paying a dividend?   
      
      
   >> Another notable feature of Z hardware is the virtualisation   
   >> technology inherent in the "hardware". So it all comes with multiple   
   >> Logical PARtitions or LPARs which despite their name are more like   
   >> physical partitioning of the hardware, and zVM which uses the "Start   
   >> Interpretive Execution" (SIE) instruction to create Virtual   
   >> Machines.   
   >   
   > Does that sound like there are a limited number of slots for   
   > instantiating virtual machines? Modern virtualization architectures   
   > aren’t limited like that.   
   >   
      
   Interesting point. So LPARS are physical partitioning. I guess almost a   
   type-0 hypervisor. You can't over commit. However its part of the   
   hardware so basically "free". Given you get a minimum of 68 cores in any   
   current Z box it isn't usually a problem. If you need to over-commit   
   then you can buy zVM a type-1 hypervisor which is really a re-badged   
   VM/XA from the 1970s.   
      
   Its interesting you say "modern virtualisation" because most of the   
   various "tweaks and tricks" modern X64 virtualisations use were   
   developed by IBM in the 1970s an 80s for VM/XA & VM/ESA. X86 and AMD   
   CPUs didn't get these until 2005/6. zVM is really slick... but expensive.   
      
      
   >> .. lets face it the competition such as pr1mos, hp-ux , Solaris, GCOS6   
   >> are all in simiular states of decline...   
   >   
   > Are new installations of any of those still being sold? Somehow I don’t   
   > think so ...   
      
   Are new installations of VMS still being sold?  So you can buy Solaris   
   and I think HP-UX, not sure about GCOS6 but from a conversation I had at   
   the weekend about a DPS6 at a local computer museum, I understand its   
   still in use in nuclear power stations, apparently because Digital no   
   longer wanted that business.   
      
   Dave   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)