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I'll definitely yield to your experience. What exactly makes the mainframes so much more capable? How does it compare to something like an SGI Altix cluster wit

I'll definitely yield to your experience. What exactly makes the mainframes so much more capable? How does it compare to something like an SGI Altix cluster with 2048-core / 16TB single system image capacity?

gaius 16y ago
The mainframe is built from the ground up for transaction processing. Have a look around Wikipedia for terms like: CICS, IMS, TPF, Sysplex, WLM. Everything, the hardware, the kernel, the rest of the OS, the programming model, the languages - all for this. It has no pretence of being a general-purpose computing platform. The mainframe would suck for what you'd use the Altix for, e.g. weather forecasting. The Altix has a lot of processes that want to work on a common dataset, but it would grind to a halt if you tried to use its interconnect to serialize transactions.
- rbranson 16y ago
  Exactly what makes it so much more useful for transaction processing? I'm looking at these things you suggested, but how does CICS compare to something like BEA Tuxedo? Of course there are no benchmarks or talk of performance out in the open on the web because I'm sure their licensing agreements forbid that. Do mainframes have some kind of crazy low-latency or high bandwidth bus that something like the Altix is missing? It appears they use similar hardware architectures, at least from a high level: super high speed modular backplanes with blade servers that form a single system image. The NUMALink 5 is stated as having 15GB/s of bandwidth (7.5GB/s in each direction) with a ~1µsec latency.
  - gaius 16y ago
    A mainframe is to transaction processing as a GPU is to 3D graphics. Does that make sense?
    - rbranson 16y ago
      No, you are being extremely vague. A GPU only performs well at executing a small set of mathematical instructions in a very specific, ultra-parallelized model against limited sets of data. They are not Von Neumann machines. A mainframe runs business software on general purpose CPUs with a normal memory model. It wasn't long ago that Macs and IBM mainframes shared the same CPUs. Yes, they support virtualization in hardware, but so do cheap Intel processors now. They appear to be architecturally no different than large SMP boxes. Please enlighten me on the key hardware differences that make them so apt for transaction processing.
    - gaius 16y ago
      Heh, I suggest you do a little reading around the architecture and the way SAPs interact with the main processor(s). Or we can just say that all languages that are Turing complete are equivalent...

gaius 16y ago

The mainframe is built from the ground up for transaction processing. Have a look around Wikipedia for terms like: CICS, IMS, TPF, Sysplex, WLM. Everything, the hardware, the kernel, the rest of the OS, the programming model, the languages - all for this. It has no pretence of being a general-purpose computing platform. The mainframe would suck for what you'd use the Altix for, e.g. weather forecasting. The Altix has a lot of processes that want to work on a common dataset, but it would grind to a halt if you tried to use its interconnect to serialize transactions.

rbranson 16y ago
Exactly what makes it so much more useful for transaction processing? I'm looking at these things you suggested, but how does CICS compare to something like BEA Tuxedo? Of course there are no benchmarks or talk of performance out in the open on the web because I'm sure their licensing agreements forbid that. Do mainframes have some kind of crazy low-latency or high bandwidth bus that something like the Altix is missing? It appears they use similar hardware architectures, at least from a high level: super high speed modular backplanes with blade servers that form a single system image. The NUMALink 5 is stated as having 15GB/s of bandwidth (7.5GB/s in each direction) with a ~1µsec latency.
- gaius 16y ago
  A mainframe is to transaction processing as a GPU is to 3D graphics. Does that make sense?
  - rbranson 16y ago
    No, you are being extremely vague. A GPU only performs well at executing a small set of mathematical instructions in a very specific, ultra-parallelized model against limited sets of data. They are not Von Neumann machines. A mainframe runs business software on general purpose CPUs with a normal memory model. It wasn't long ago that Macs and IBM mainframes shared the same CPUs. Yes, they support virtualization in hardware, but so do cheap Intel processors now. They appear to be architecturally no different than large SMP boxes. Please enlighten me on the key hardware differences that make them so apt for transaction processing.
  - gaius 16y ago
    Heh, I suggest you do a little reading around the architecture and the way SAPs interact with the main processor(s). Or we can just say that all languages that are Turing complete are equivalent...