Linked by David Adams on Wed 7th Sep 2011 21:15 UTC, submitted by sjvn
Ubuntu, Kubuntu, Xubuntu Sources close to Canonical and IBM are telling me that Ubuntu may soon be certified on IBM's System p mini-computers and blades and System z mainframes.
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Why run Linux on a slow Mainframe?
by Kebabbert on Fri 9th Sep 2011 09:02 UTC
Kebabbert
Member since:
2007-07-27

Mainframe cpus are much much slower than x86 cpus. Any decent Quad core x86 cpu is much faster than the newest and fastest Mainframe cpu. So why would anyone want to run Linux on slow extremely expensive hardware?

Look at dhrystone mips, and compare the latest and fastest z196 Mainframe cpu vs Quad Core i7: 50.000 MIPS vs 160.000MIPS
http://en.wikipedia.org/wiki/Instructions_per_second#Timeline_of_in...

Reply Score: 2

Lennie Member since:
2007-09-22

I think because a System Z10 is fully redundant (including for example memory) and can run many, many Linux machines.

Sometimes you don't need the all that CPU-power just a lot of different machines.

Running just the 'one' system is a lot more power and cooling efficient than a large number of Intel-based machines.

Some even support water-cooled.

And because of the redundancy it is very reliable.

Reply Parent Score: 2

foobar Member since:
2006-02-07

Those aren't drystone MIPS in the table for z196. They are the zMIPS mentioned earlier in the article. You are comparing different units and drawing incorrect conclusions.

Reply Parent Score: 1

Kebabbert Member since:
2007-07-27

Those aren't drystone MIPS in the table for z196. They are the zMIPS mentioned earlier in the article. You are comparing different units and drawing incorrect conclusions.

Yes I know it is different MIPS, I am aware of that.

However, there are other links that show IBM Mainframe cpus are slow, as well.

Here are some numbers that show how slow IBM Mainframe cpus are:
http://www.osnews.com/thread?419352

Reply Parent Score: 2

Subcomputer Member since:
2011-01-21

People who keep coming into these topics and talking about just cpu power seriously need to do some research.
Because in the enterprise sector raw cpu power doesn't mean nearly as much as i/o ability and redundancy. Most servers actually sit with the cpu idling while waiting for disk or network access. This is why virtualization is becoming so common.
Secondly, mainframe architecture is very different from small systems. In a small system the cpu handles darn near everything, so it needs to be high powered. In a mainframe, all i/o is relegated to specialized processors, and there are specialized processors for Java and database programs.
A mainframe is in fact a cluster, so tightly integrated that only the head sysadmin needs to know/care.

Reply Parent Score: 1

Kebabbert Member since:
2007-07-27

People who keep coming into these topics and talking about just cpu power seriously need to do some research.
Because in the enterprise sector raw cpu power doesn't mean nearly as much as i/o ability and redundancy. Most servers actually sit with the cpu idling while waiting for disk or network access. This is why virtualization is becoming so common.
Secondly, mainframe architecture is very different from small systems. In a small system the cpu handles darn near everything, so it needs to be high powered. In a mainframe, all i/o is relegated to specialized processors, and there are specialized processors for Java and database programs.
A mainframe is in fact a cluster, so tightly integrated that only the head sysadmin needs to know/care.

So what? I claim that IBM Mainframe cpus are several times slower than a high end x86 cpu. I dont see that you deny that. You are talking about good I/O, etc - I have never talked about Mainframe I/O. Are you trying to shift focus away from the slow Mainframe cpus, and try to make me say things I never said about I/O?

Thus, the IBM Mainframe cpus are several times slower than a high end x86 cpu. Look in a post higher up, by me, for more information about the slowness of IBM Mainframe cpus.

Here is more information about the latest IBM Mainframe cpu, the Z196, which runs at 5.26GHz and has close to half a GB of cpu cache. IBM dubs this the "Worlds Fastest CPU" - which is quite dubios advertising.
http://www-03.ibm.com/press/us/en/pressrelease/32414.wss

PS. I dont understand how IBM can claim that a big Mainframe can virtualize 1.500 x86 servers, when there is no way that 24 slow Mainframe cpus can do the work of much faster 1.500 x86 cpus?

Reply Parent Score: 2