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> On the other hand, you can get rack-mount x86 server with several TB of RAM for fraction of price of mainframe which is exactly the hardware for new applicati

by mmt 8y ago

> On the other hand, you can get rack-mount x86 server with several TB of RAM for fraction of price of mainframe which is exactly the hardware for new applications that would otherwise be best served by mainframe. I expect the largest one of these is still a fraction the size of the largest mainframe, at least for processor power (e.g. 224 cores[0] compared to 1700[1]). Maximum memory, though, is 32TB, which isn't exactly huge compared to 12TB [0] or 24TB [2]. [0] https://www.supermicro.com/products/system/7U/7089/SYS-7089P-TR4T.cfm https://www.supermicro.com/products/system/7U/7089/SYS-7089P... [1] https://en.wikipedia.org/wiki/IBM_zEnterprise_System#z14 https://en.wikipedia.org/wiki/IBM_zEnterprise_System#z14 (Not saying they're necessarily equivalent in performance, but they might be, as you point out) [2] https://www.supermicro.com/products/system/7U/7088/SYS-7088B-TR4FT.cfm https://www.supermicro.com/products/system/7U/7088/SYS-7088B...

dfox 8y ago
From my point of view for typical modern bussiness workloads that necessiate large machines (ie. SQL RDBMS or something similar) only thing that you really care about is memory size. On the other hand many "legacy" mainframe workloads are significantly more CPU-bound because the software culture is simply different and brute force is often the way to go.
- mmt 8y ago
  > From my point of view for typical modern bussiness workloads that necessiate large machines (ie. SQL RDBMS or something similar) only thing that you really care about is memory size. That's my general impression, as well, but I have little enough (or inadequately broad) direct experience for that impression to be a strong one. I've also seen, second-hand (i.e. benchmarks, so not quite real-world) that cache and memory latencies (including inter-CPU/NUMA) can significantly affect OLTP performance. If that weren't true in practice, then the sheer bandwidth one can deliver from enough SSDs over PCIe rivaling a CPU's memory bandwidth would mean main memory size is much less relevant.

by mmt 8y ago

dfox 8y ago

From my point of view for typical modern bussiness workloads that necessiate large machines (ie. SQL RDBMS or something similar) only thing that you really care about is memory size. On the other hand many "legacy" mainframe workloads are significantly more CPU-bound because the software culture is simply different and brute force is often the way to go.

mmt 8y ago
> From my point of view for typical modern bussiness workloads that necessiate large machines (ie. SQL RDBMS or something similar) only thing that you really care about is memory size. That's my general impression, as well, but I have little enough (or inadequately broad) direct experience for that impression to be a strong one. I've also seen, second-hand (i.e. benchmarks, so not quite real-world) that cache and memory latencies (including inter-CPU/NUMA) can significantly affect OLTP performance. If that weren't true in practice, then the sheer bandwidth one can deliver from enough SSDs over PCIe rivaling a CPU's memory bandwidth would mean main memory size is much less relevant.