Interesting. Do you have any numbers on how much overhead? Is it 10% or 80%? I plan to use LACP too but my intent is more for high availability that high bandwidth. If I dual path OSA's and Cisco 3750 switch ports into zVM VSWITCH I would rather use both ports than have one sitting in standby. Personally I am not impressed that you must dedicate OSAs to a Link Aggregation VSWITCH since I would just as soon EMIF and share this to 2 zVM LPARS. I am still interested in the overhead of LACP.
Al Schilla Systems Programmer Enterprise Technology Services Office of Enterprise Technologies phone: 651-201-1216 email: alan.schi...@state.mn.us -----Original Message----- From: Linux on 390 Port [mailto:linux-...@vm.marist.edu] On Behalf Of Harder, Pieter Sent: Friday, May 01, 2009 6:26 AM To: LINUX-390@vm.marist.edu Subject: Re: TSM Server on Linux on Z Anyone? Hi John, >We are considering Linux on z9, and I noticed you mentioning the overhead of >VSWITCH LACP - which we are planning to use. Do you have some detailed >information on this overhead? Is it affected by SET PORT GROUP INTERVAL ? >Any information would be gratefully received :-) The problem is not with LACP per se, but with VSWITCH in general. The problem is that communication through VSWITCH is a two step process. One step involves moving data from the OSA buffers to CP buffers and is assisted by the OSA hardware. The second step involves CP inspecting the data and moving it to/from the target stack buffers within the guest. This second step is totally within software and inevitably produces a lot of overhead. This becomes quite noticeable with the large amounts of data that LACP can handle from a hardware point of view. In our case we cut out the middle man and have the data delivered to target stack buffers directly by the OSA hardware. The drawback to this is that you have to dedicate the OSA chpid to the guest. But then when you are trying to move hundreds of megabytes a second to one guest, and OSA's being a lot cheaper than IFL's, that is the more acceptable solution. Best regards, Pieter Harder pieter.har...@brabantwater.nl tel +31-73-6837133 / +31-6-47272537 Brabant Water N.V. Postbus 1068 5200 BC 's-Hertogenbosch http://www.brabantwater.nl Handelsregister: 16005077 ---------------------------------------------------------------------- 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 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
