> On 26 Aug 2023, at 9:55 am, Jon Perryman <jperr...@pacbell.net> wrote: > > I think z/OS uptime is 99.9999%.
I don’t think so. IBM claim 99.999% single server uptime for z and that’s just the hardware. That’s the same as they claim for POWER running either AIX or Linux on RedHat Open Shift and what HP claim for Superdomes running HP-UX. They all claim higher then five-nines running in clusters. What this boils down to is there is redundancy in the hardware for PDUs, Network card, I/O adapters. My bank runs a mainframe and I couldn’t use internet banking when abroad because they were running month-end scheduled maintenance. Many providers claiming five-nines availability will add small print to get around this problem. By excluding scheduled downtime, five-nines becomes a lot easier. > You get what you pay for. Unix maint philosophy may be acceptable on $10,000 > computers but highly unacceptable on multi-million $ computers. We don't > tolerate unintentional downtime. That doesn’t stand up to scrutiny! Just ask Air New Zealand in 2009, HSBC in 2011, or the Royal Bank of Scotland in 2013. The fact is that even five-nines availability for an entire computing service is impossible to guarantee. There is too little room for error and Black Swan or unexpected events are impossible to eliminate. If you have access to the IBM support portal go and do a search for z/OS Red Alerts. Software has bugs, applications and subsystems fail. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
