It really depends on how easy/hard is it, in your shop to change the size of the LPAR. When it is easy, then I make the memory allocation fairly small, say 2 GB and grow it when it is proved that I need more memory. However, I wouldn't ever try Websphere with anything under 4 GB. This is under the theory that the first application takes all the memory it can and will leave nothing for the next application. I have a 4 GB LPAR for z/VM 5.2 and Linux machines. What I currently have running: I have 18 Linux images running 1 production Oracle 1 test Oracle 1 development Oracle 1 DB2 Connect production 1 DB2 Connect test 4 Samba servers (SLES 8) 2 NFS servers 2 FTP servers (that have the iso images of Linux and Oracle mounted for installation purposes) 3 VSE Virtual Tape servers 2 Samba Servers (SLES 11) that will be migrating to once testing is completed (these will also take over the VSE LANRES disk hosting function we are currently using) None of these are heavy hitters. Production Oracle has 200 users defined and 40 currently logged on. DB2 Connect production has 22 clients at this time. The VM system only pages when an image is bought up. All the linux images use vdisk for swap space. The production DB2 Connect image: Defined as 250 MB virtual. Defined on a single 3390-9. Has been running for 162 days; linux69:~ # swapon -s Filename Type Size Used Priority /dev/dasdb1 partition 162468 2712 50 /dev/dasdc1 partition 81228 45224 60 Most of the swap space used was from me going into Yast. And as VMSTAT shows, we are not actively swapping: linux69:~ # vmstat 10 10 procs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------ r b swpd free buff cache si so bi bo in cs us sy id wa st 1 0 47936 7680 22460 124440 0 0 2 15 1 0 4 1 94 0 1 0 0 47936 7560 22468 124432 0 0 0 14 2631 165 4 1 70 0 25 0 0 47936 7560 22476 124424 0 0 0 3 3130 179 4 1 80 0 15 0 0 47936 8092 22432 124468 0 0 0 18 351 213 4 1 95 0 0 0 0 47936 8032 22448 124452 0 0 0 14 328 203 3 1 95 0 0 0 0 47936 8032 22456 124444 0 0 0 12 5486 188 0 1 99 0 0 0 0 47936 8032 22472 124428 0 0 0 26 6104 189 4 1 89 0 6 0 0 47936 8032 22496 124404 0 0 0 14 6267 189 4 1 88 0 7 0 0 47936 7972 22520 124380 0 0 0 14 4529 194 4 1 86 0 9 0 0 47936 7972 22536 124364 0 0 0 12 996 202 4 1 95 0 1
So, your initial plans for a z/VM plus a single DB2 Connect Server could be run in a LPAR of 512 MB. However, since SUSE (with OSA connections) seems to want about 750 MB for installation, that would cause a lot of paging when you do a Linux install. On a MP3000 with 1 GB and 9 VSE systems the 750 install requirement did cause a lot of paging but everything still ran fairly well. My current processor is a z/890 with a ficon attached DS6800. So, yes, I do trade the very cheap ficon I/Os for the more expensive memory. If we were driving the DS6800 harder, then I would add more real memory to the mix to drive down the I/O rate (paging/swaping reduction along with more memory for caching). So the question goes back to....What else are you planning (or playing) for in the future and how often can you reconfigure the LPAR to add more memory? Tom Duerbusch THD Consulting >>> "Dazzo, Matt" <mda...@pch.com> 12/2/2010 8:45 AM >>> We are entering the world of zvm/linux with a z10bc-2098 n04 and 16gb total memory. I am trying to decided what to allocate to zvm/linux as a starting point. Our initial thoughts and a recommendation from our VAR was 6gb. The first application will be DB2 Conn Server and not sure what's after that. I'd like to find out how much memory other shops have allocated and what applications they support. Is our initial 6gb a decent starting point? I know the IBM standard answer 'it depends' but I am looking for some clarity and guide lines. Thanks Matt ---------------------------------------------------------------------- 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/
