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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.arch
Subject: Re: Article on new mainframe use
Date: Fri, 16 Aug 2024 00:12:32 +0300
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On Thu, 15 Aug 2024 17:44:42 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:

> On Thu, 15 Aug 2024 0:02:11 +0000, Lawrence D'Oliveiro wrote:
>=20
> >
> > Mainframes are obsolete. The mindset of =E2=80=9Cthe CPU is expensive, =
let=E2=80=99s
> > surround it with complex channel controllers to handle batch I/O=E2=80=
=9D
> > stopped being relevant sometime in the 1980s, if not before. =20
>=20
> If one defines a mainframe computer as having the ability to remove
> and replace every component without taking the computer off line--then
> mainframes are still relevant. Reliability, Availability,
> Serviceability.
>=20
> And when I say everything I mean everything:
> power supplies, memories, disks, NICs, other devices, CPUs, cooling,
> ..
>

And then there comes an electrician and pulls big red switch. Twice.
And after that it turns out that live link to reserved computer 20 miles
apart and the whole restart procedure was never tested.
That's exactly what happened in Heathrow not so many (7) years ago.

It was never confirmed that computers in fault were IBM mainframes, but
what else it could have possibly been?

> Reliability may trade speed for never failing as a good trade off
> Availability 100% up time 24/7/365 for a decade or longer without
> outages
> Serviceability replacement of any and all modules while keeping the
> system "up"
>=20
> Thus a mainframe is more about how it is constructed than what parts
> are used to construct it.