Hi Carsten, i just don't believe that under stress conditions that in today's environement you can show value to paging to dcss over vdisk. This being with z/vm 5.1 and a current redhat or suse.
The ibm recomendations i keep hearing being repeated are that swap sizes must be some multiple of the linux virtual machine size. So if my Oracle server requires 2GB, then (some) ibm do says i should have 4GB of swap. and in today's environement, i can not have a discontigous virtual machine, so swap dcss must be at the top of virtual storage. but that would be over the 2gb line. not possible - with what is available or announced as far as i know. mixing dcss and vdisk seems to create a more complex environment than most installations want to utilize. after all, vm is just a hypervisor i'm told. even if discontigous machines were supported by linux and z/vm, i still don't have 2gb available of virtual storage for the dcss, unelss you eliminate all need for linux to address storage below the 2gb line? In real production environements, i currently have a serious problem with storage and minimizing storage requirements. i believe that with the current vdisk and dcss page stealing algorithms, that dcss will retain more real storage than vdisk. much more. and i think vdisk could be greatly improved upon. so really, my main point i'm trying to make is that a real measurement showing value is worth a lot of opinions.... i have mine, you have yours, rob has his, let's duke it out on the benchmark battlefield.... show real data???? winner buys the beer? >From: Carsten Otte <[EMAIL PROTECTED]> > >Hi Barton, > >today you have a full 2G of space for dcsses available - even >when using lage main memory. You can use dcss swapping with >oracle, and all other apps you have in mind. You can mix >different swapping devices easily with Linux, you can even >priorize using them. When you need 500gig of swap, you can use >2gig dcss high prio, and 498gig on dasds. The VM paging priority >issue you describe does not apply to DCSS based swap. > >What's your point? > >with kind regards >Carsten Otte "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
