Re: [PLUG] Why mainframes excel: was How the IRS is able to reverse engi

Re: [PLUG] Why mainframes excel: was How the IRS is able to reverse engineer Assembly

Best regards,

//CMFM

On Fri, Feb 9, 2018 at 12:30 PM, K.S. Bhaskar <bhaskar@bhaskars.com> wrote:

Mainframes are not the most powerful computers these days. Once upon a time (through the 1980s) they had the fastest CPU, the most memory, and the highest IO throughput. Then computer systems with CPUs like the DEC Alpha started surpassing mainframes, first in computing capability and then in RAM. Storage connected by fiber channel meant that mainframes were no longer the IO throughput champions either – everyone was on a level field. That's why, circa 2000, IBM went through a major re-branding exercise, and mainframes became zSeries (z for zero down-time), the RS/6000 became the pSeries (p for power), the System 38 (if I remember my numbers correctly) became iSeries (i for integrated), and the x86 based machines became xSeries (x for x86).

Today's champions are all x86 architecture based machines. But zSeries mainframes run programs written in the 1960s, written in COBOL, operationally managed by JCL, using databases like DB2 and IMS, and transaction monitors like CICS. For enterprises, it's often cheaper and less risky to pay the extra $$$ for mainframes than to port, rewrite, or replace the applications.

Regards
– Bhaskar

On Fri, Feb 9, 2018 at 11:40 AM, Steve Litt <slitt@troubleshooters.com> wrote:
On Thu, 8 Feb 2018 20:34:32 -0800
Lowell Higley <higleylh@gmail.com> wrote:

> Whether you know it or not, you probably touch a MF dozens of time
> every day.. airlines.. banks.. financial markets.. insurance. All run
> by mainframes. You pay social security or get a social security
> check? Yup, you guessed it.. all run on mainframes. Greater than 90%
> chance that when you use your mobile phone to check your bank account
> balance - you're touching a mainframe on the backend.
>
> An insurance company that will remain nameless for the purpose of this
> message has been trying to leave the MF for almost a decade (a M$
> alum sits on their board). They've only been able to successfully
> port one application (starting from scratch) and it's always down and
> generally performs like @(#*. Without MFs your interactions with
> many companies would be much worse than they are today (definitely
> not saying it's perfect today.) Even as "expensive" and "antiquated"
> as they are (the mainframe will turn 55 in 2019), they arguably still
> out perform and - especially when you factor in all the indirect
> costs - cost less than other platforms.

I've heard this from enough mainframe-knowledgeable people that I
believe it, so the next question is, how does the mainframe bestow so
much power? It seems to me that it wouldn't be hard to put a few
terabytes of RAM on a board. With 64 bit addressing it would be no
problem to use it all. It would also be easy to put a bunch of
processors on the system. I've heard the mainframe's real advantage is
its bus, but I haven't heard the details.

So how do mainframes derive their power?

SteveT
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___________________________________________________________________________
Philadelphia Linux Users Group -- http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug