Thanks Ingo (and Scott)! 1) The app runs under IIB 2) We're running z/VM 6.3 (soon 6.4) in a four-member cluster 3) We have more real IFLs in each member than vCPUs on any of the guests 4) We have a ways to go before we get to the 64-CPU limit
My main question is how well Linux itself scales as vCPUs increase. Does the SMP penalty outweigh the z/VM penalty associated with handling more aggregate vCPUs? For example, would I be better off adding two vCPUs to each of the eight guests (total of 80), or add two more eight-vCPU guests (total of 80)? As a more radical option, how would four guests with twenty vCPUs each (total of 80) work? Best regards, Mark -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Ingo Adlung Sent: Monday, April 03, 2017 10:00 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: RHEL 6 CPU Scalability It really depends on the workload whether scale-up or scale-out is better suited. With z/VM 6.3 you should be well prepared for both options (as you are with running Linux in LPAR) but it is really a workload question. E.g. many applications would allow for scale-out clustering at linear scale, while e.g. databases would require for data sharding in a scale-out model if scale-up is not an option. In any case don't define more vCPUs to a single virtual machine than you have logical CPUs defined to your LPAR as also Scott pointed out. Now this said, if your capacity needs keep growing and the concurrent, aggregated CPU capacity needs exceed 64 cores (or 32 cores running SMT2 giving you 64 HW threads) you may need spilling over into an additional z/VM instance anyhow ... Mit freundlichem Gruß / Best regards Ingo Adlung Ingo Adlung IBM Deutschland Research & IBM Distinguished Engineer Development GmbH Chief Architect, and CTO Vorsitzender des Aufsichtsrats: z Systems and LinuxONE Martina Koederitz Virtualization & Linux Geschäftsführung: Dirk Wittkopp mail: adl...@de.ibm.com Sitz der Gesellschaft: Böblingen phone: +49-7031-16-4263 Registergericht: Amtsgericht Stuttgart, HRB 243294 Linux on 390 Port <LINUX-390@VM.MARIST.EDU> wrote on 03.04.2017 15:46:38: > From: "Wheeler, Mark L" <mark_whee...@optum.com> > To: LINUX-390@VM.MARIST.EDU > Date: 03.04.2017 15:47 > Subject: [LINUX-390] RHEL 6 CPU Scalability Sent by: Linux on 390 Port > <LINUX-390@VM.MARIST.EDU> > > Greetings! > > We have eight RHEL 6 servers with 8 vCPUs each handling a large > workload, which continues to grow. We could expand the server farm > horizontally by adding more servers, or vertically by adding more > vCPUs. I'm concerned about SMP effects of adding more vCPUs but don't > have any data to validate that concern one way or another. > > Can anyone provide a recommendation? More servers or more vCPUs? > > Very best regards, > > Mark Wheeler > z/VM and zLinux > Optum Technology > 952-912-9524 > Mark_Wheeler at optum.com > > > This e-mail, including attachments, may include confidential and/or > proprietary information, and may be used only by the person or entity > to which it is addressed. If the reader of this e-mail is not the intended > recipient or his or her authorized agent, the reader is hereby > notified that any dissemination, distribution or copying of this > e-mail is prohibited. If you have received this e-mail in error, > please notify the sender by replying to this message and delete this e-mail > immediately. > > ---------------------------------------------------------------------- > 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/ > ---------------------------------------------------------------------- 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/ This e-mail, including attachments, may include confidential and/or proprietary information, and may be used only by the person or entity to which it is addressed. If the reader of this e-mail is not the intended recipient or his or her authorized agent, the reader is hereby notified that any dissemination, distribution or copying of this e-mail is prohibited. If you have received this e-mail in error, please notify the sender by replying to this message and delete this e-mail immediately. ---------------------------------------------------------------------- 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/
