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Some extra information about ibm mainframes
by zubzub on Fri 16th Apr 2010 08:37 UTC
zubzub
Member since:
2010-04-16

Some people posting here don't seem very well informed...

First.
the unix layer for z/OS exists for quite a while now (more than 10 years iirc). So it's nothing new. It was developed when ibm though mainframes would become obsolete and everything would be run by (unix) server farms. A unix layer for z/OS would be a good argument to keep the mainframe hardware running.

Second.
Some people are comparing mainframes in general with x86 in general and conclude that x86 is faster.
This doesn't make sense at all. The z10 that was releassed in 2008 can have up to 1.5 terabyte of RAM and can have up to 77 quadcore ppc based PUs operating at 4.4Ghz each. Eliminate all the overhead you have with clustered server farms running linux/unix/windows and you have a beast roughly equivalent with 1000 x86 based servers.

Edited 2010-04-16 08:40 UTC

Reply Score: 1

Kebabbert Member since:
2007-07-27

You have been fooled by IBM marketing. IBM was the first company to employ FUD on a wider scale. IBM is famous for foul play and FUD.
http://en.wikipedia.org/wiki/Fear,_uncertainty_and_doubt#Definition


Regarding the performance of Mainframes. A z10 with 64 cpus, give 28.000 MIPS. An 8-socket Nehalem-EX gives 3.200 MIPS - under software emulation. Software emulation is 5-10 times faster than native code. If Nehalem-EX could run Mainframe software natively, 8 x86 cpus would give 16.000 - 32.0000 MIPS. You need 8 Intel x86 cpus to match 64 Mainframe cpus.
http://en.wikipedia.org/wiki/Hercules_emulator#Performance

Mainframes are good for different things, but cpu speed is not one of them.





Also, another source, an Linux expert who ported Linux to mainframes, claimed year 2003, that 1 MIPS == 4 x86 MHz. Hence, 28.000 MIPS corresponds to 112GHz. Pick a 8 core Nehalem-EX, which runs at 2.3GHz = 8 x 2.3 GHz = 18.4GHz. But, Nehalem-EX is much faster clock for clock, than Pentium 4. Whereas 1 MIPS then, is 1 MIPS today. Nehalem-EX may be 2 times faster than one Pentium 4, at same clock speed. Then those 18.4GHz of Pentium 4 MHz, corresponds to todays 36.8GHz. You need just a few of Nehalem-EX to match 28.000 MIPS.
http://www.mail-archive.com/linux-390@vm.marist.edu/msg18587.html

You have two independent sources, who port Linux to Mainframes, or write Mainframe emulators - that states that Mainframe CPU is dog slow.

Also, IBM never publishes Mainframe benchmarks. When IBM has some good number, IBM brags about it all the time. For instance POWER7 is much faster than an Mainframe cpu, and IBM has released POWER7 benches, and brags about it all the time. (POWER7 is a good cpu, Mainframe cpus sucks).



@foobar,
See above.

Reply Parent Score: 2

foobar Member since:
2006-02-07

Regarding the performance of Mainframes. A z10 with 64 cpus, give 28.000 MIPS.


It is actually 30,657 MIPS.

http://www-05.ibm.com/pt/systems/z/news/technical.pdf

An 8-socket Nehalem-EX gives 3.200 MIPS - under software emulation. Software emulation is 5-10 times faster than native code. If Nehalem-EX could run Mainframe software natively, 8 x86 cpus would give 16.000 - 32.0000 MIPS. You need 8 Intel x86 cpus to match 64 Mainframe cpus.
http://en.wikipedia.org/wiki/Hercules_emulator#Performance


According to that wikipedia article, Hercules emulation is 5-10 times slower. Also, they are predicting 3,200 MIPS for an entire 8 processor Nehalem machine. They haven't actually measured it yet. So you need 8 x86 machines each with 8 Nehalem chips running a tight loop of hand optimized s390 assembler to match a z10.

Mainframes are good for different things, but cpu speed is not one of them.


That has been changing since z9...





Also, another source, an Linux expert who ported Linux to mainframes, claimed year 2003, that 1 MIPS == 4 x86 MHz. Hence, 28.000 MIPS corresponds to 112GHz. Pick a 8 core Nehalem-EX, which runs at 2.3GHz = 8 x 2.3 GHz = 18.4GHz. But, Nehalem-EX is much faster clock for clock, than Pentium 4. Whereas 1 MIPS then, is 1 MIPS today. Nehalem-EX may be 2 times faster than one Pentium 4, at same clock speed. Then those 18.4GHz of Pentium 4 MHz, corresponds to todays 36.8GHz. You need just a few of Nehalem-EX to match 28.000 MIPS.
http://www.mail-archive.com/linux-390@vm.marist.edu/msg18587.html


and you are still quoting these z990 numbers from 2003, so you haven't noticed... er uh chose to ignore it.

You have two independent sources, who port Linux to Mainframes, or write Mainframe emulators - that states that Mainframe CPU is dog slow.


Rubish, you're twisting the numbers and conveniently leaving facts out.

Also, IBM never publishes Mainframe benchmarks. When IBM has some good number, IBM brags about it all the time. For instance POWER7 is much faster than an Mainframe cpu, and IBM has released POWER7 benches, and brags about it all the time. (POWER7 is a good cpu, Mainframe cpus sucks).


There is lots of mainframe performance info out there. You just don't know where to look. Go check out share.org.

Reply Parent Score: 1