First, use Ficon. performance is SIGNIFICANTLY better than Escon. Channels for VM Paging (vm does paging, not swapping) is rarely an issue. Escon channels to me are a huge inhibitor to LInux on z/VM performance.
There has been no published research for SAP performance under Linux under z/VM. There IS however work on a redbook for Oracle under linux under z/VM that will hopefully be published or at least partially distributed. I've been working on the performance part of that. I've looked at some SAP data but i think some extended research is needed. The overcommit question is not easy, there are several issues to address first. Do your servers drop from queue? This allows VM storage management to page servers out and is critical. Do you use virtual disk for linux swap? and have minimized the virtual machine size? This reduces overall requirements. Can you determine what percent of time your servers are active? if all your servers are active at the same time, you need storage to satisfy all of the active requirements. There was a z/VM performance class scheduled last month in Munich. Another class has not as of yet been scheduled. Check "www.velocitysoftware.com" for z/VM performance education schedules. >From: Lufthansa Systems Infratec ZLINUX SYSPROG <[EMAIL PROTECTED]> > >Dear all, > >there is a lot to read about z/VM and Linux performance. Also >about memory over commit. but I didn`t find "real life" >performance data about zLinux & SAP or Oracle or Tomcat (nor >other "standard" Application-Server) and how the perform while >over commit memory. > >A special point of interest would be: >- How many escon-channels do you use for swap under z/VM ? >- How much (in percent) do you over commit memory for a Linux-guest ? >- What`s about fibre-channel ? Is there a much better performance and is >it possible to do much more memory over commit ? > >- If yes, how much more ? > >As I can say so far, 20% memory over commitment in general >works. We us 4 escon-channels to the z/VM swap-devices. > >I would be happy, if someone can share some "real life" >experience with us. > >Regards, > >Martin Lonkwitz > >Martin Lonkwitz Lufthansa Systems GmbH > >UNIX Systems Engineer FRA AR/ISS > >Systemplanung,-betrieb Am Weiher 24 > >und Entwicklung D-65451 Kelsterbach > > Telefon:(069) 696-72456 > >Externer Servicepartner der Firma > >networker, projektberatung GmbH > >Am Kaltenborn 1 > >61462 K=F6nigstein "If you can't measure it, I'm Just NOT interested!"(tm) /************************************************************/ Barton Robinson - CBW Internet: [EMAIL PROTECTED] Velocity Software, Inc Mailing Address: 196-D Castro Street P.O. Box 390640 Mountain View, CA 94041 Mountain View, CA 94039-0640 VM Performance Hotline: 650-964-8867 Fax: 650-964-9012 Web Page: WWW.VELOCITY-SOFTWARE.COM /************************************************************/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
