On 07.11.2017 23:04, John Campbell wrote: > 1) On the kind of workload (compute vs I/O) > 2) Requirements for reliability (look at Appendix A? from "Linux for the > S/390") > > There is no simple answer to this. I suspect there are some benchmarking > tools that will help. > > The zSeries is AT LEAST 5 9's hardware.
Does that matter in today's world? Would you avoid building for failure when a lot of the failure comes from software anyway? Do you then host multiple Linux VMs on the same iron to account for that? If so, why can't that scale horizontally? > Because Windows runs on Intels, seldom do they need to consider much better > than 9 5's reliability. (smirks) That's not how reliability works. > A mainframe CPU provides: > > a) Maximum reliable single-thread compute performance; Fair. Although I suppose POWER8 comes close? > b) Maximum I/O connectivity; and > c) Maximum I/O throughput. Depends on your storage rack and connectivity, doesn't it? > On an I/O intensive workload I do not see an intel as being competitive. If you look at, say, Google Compute Engine with Local SSD[1] it has some pretty impressive IOPS numbers. Yes, it's not replicated. > IIRC most of the folks doing heavy computing-- like Bitcoin mining-- use > the display adapter's GPU for the heavy lifting, which leaves the zSeries > at a disadvantage. I wonder what all these newfangled blockchain technologies use in the backgrounds. (The ones that aren't currencies but "just" ledgers.) > So, like I said above, "it depends". > > What's the workload? > > What do you need the most "heavy lifting" for? > > Mind you, if you need to run multiple instances on the same IFL, well, > you're going to have to minimize CPU overcommitment. I idly wonder how actual utilization of IFLs looks like in the field. It's clear to me that CPs run hot because otherwise you're wasting moneys. I.e. if overcommitment is just a fact of life like it is in the cloud. Kind regards Philipp Kern ObNote: Although I work for Google as a reliability engineer I speak as a private person who is curious about mainframes. [1] https://cloud.google.com/compute/docs/disks/performance ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
