Rob, The traffic is between our Sap application servers running under zvm.
During the latest conference call, the TCP ip folks determined that the SAP traffic in question generally has packets less than 8k. So changing the frame size would not help. Ron Foster Baldor Electric Company 5711 R S Boreham Jr Street Fort Smith, AR 72901 Phone:479-648-5865 Fax:479-646-5440 Email: ron.fos...@baldor.abb.com IM Address:rfos...@baldor.com www.baldor.com ________________________________________ From: Linux on 390 Port [LINUX-390@VM.MARIST.EDU] on behalf of Rob van der Heij [rvdh...@gmail.com] Sent: Saturday, June 15, 2013 2:05 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: Appropriate hipersocket MFS size for use with SAP Apps Servers On 13 June 2013 23:58, Ron Foster <ron.fos...@baldor.abb.com> wrote: 3. One of the things that the TCP IP folks want us to do on the hardware > side is to increase the maximum frame size to 64k. for this hipersocket. > > 4. This would normally increase the MTU size to 56k for the hipersocket. > > 5. If I remember properly the 56k value would exceed the SAP recommended > MTU size of 8k. > > 6. The IBM z/os TCP/IP support says that the MTU size could be forced to > 8k. > > Anyone have any experience in forcing an MTU to 8k like this? Any > unwelcome side effects? > The queuing that the MVS folks observe is likely in another place than the MTU size, at least there are other knobs to work first. If you only increase the MSS and MTU to the max, you may end up with throughput seriously lower than what you achieve now. I suppose the massive volumes you talk about is for the shared NFS space between the two? I can dig up some more questions for you when I get through the rest of my pending inbox (I hate when you all start these threads when I'm offline ;-) Rob ---------------------------------------------------------------------- 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/
