On 5/13/19 9:46 AM, John McKown wrote:
Yes, we have had a TCM fail. I was almost called a liar when I told the
Windows people that the z simply switch the work transparently (on the
hardware level) to another CP. They were shocked and amazed that we
could "hot swap" a new TCM into the box without any outage.
TCM as in Thermal Conduction Module?
IMHO that's mildly impressive. I say /mildly/ because I would /expect/
a mainframe to be able to survive that without (significantly) impacting
the workload.
I also would like to think that some of the more advanced schedulers in
Linux could detect that a CPU (set of cores) was overheating and needed
to be taken out of service. I would hope that if the chassis was
designed properly, a good CE could replace the TCM without taking the
machine down.
I'm also assuming that the CPU was not actually faulted and would still
pass sanity checks as long as no actual work was scheduled on it.
I know that there are Open Systems that can have the processor offlined
and replaced.
The same thing when an OSA failed.
Ya. So what. - No disrespect intended. To my naive point of view, an
OSA is a really, Really, REALLY fancy network adapter. As such, I would
/expect/ that the mainframe can offline an ultra fancy network card,
have the hardware replaced, and bring the new one online again.
Open Systems have been able to hot add and remove expansion cards like
NICs for quite a while. Granted, few OSs handle it well. But that's a
different problem.
The other OSA simply did an "ARP rollover" and there were not any
outages.
Did the new OSA assume the MAC address(es) of the old OSA? Or did you
allow other L2 connected devices to learn the new OSA's new MAC address(es)?
Sadly, IMHO, too few systems administrators have any idea what is
possible with the hardware / software / network. There are multiple
ways to deal with a failed NIC.
Sure, the OSA is a LOT fancier than the average NIC. But that just
means that there is more configuration that needs to be done to support
such a hot migration.
And that, again, IBM replaced the OSA "hot" and we simply started
using it. All automatically.
That's as I would expect it to be.
I am guessing that the mainframe, with it's longer history and more
experience, has likely refined the process more than some Open Systems
have had the opportunity to do so.
But the Windows people still chant "Windows is BETTER than the
mainframe."
Oh, come on. Windows is better at playing GUI games. ;-)
--
Grant. . . .
unix || die
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