On Thu, Apr 22, 2010 at 3:44 PM, Dean, David (I/S) <[email protected]> wrote:
> zLinux 5.4, SUSE 10.2. Running one instance of WebSphere 7 with 6 profiles > / JVM instances. I started with 3 GIG, went to 5GIG, now at 6 GIG, and free > memory still drops little by little, SWAP eventually begins to grow and > finally performance goes to heck. Just like Windows (ouch) you reboot and > everything is cool for a few more days…. > > I have read and heard the lectures on zLinux taking all you give it, but I > need it to STOP. Without useful data, one can only guess. But my guess may better than yours ;-) It's probably too early to claim a leak. It's just that you haven't seen the bottom yet. The lecture is not that Linux uses what you give it, but "what you told it could have" So when you have 7 instances in the same virtual machine, and tell each JVM they can have upto 1 GB heap (popular default, I think) then they will eventually come for that 7 GB. Apart from the JVM heap, there's the base requirement of Linux and WAS code, etc. May well add another 2 GB. You would have to talk to the WAS people and learn what they configured for the JVM maximum heap size (don't assume defaults), add that up, and size your virtual machine. There's also applications that do "automatic" sizing and just look at real memory and use that (and guess what happens when each of them did that). Like a customer who had serious problems beause the DBA had asked someone "how much memory has z/VM" and then configured all his databases to use 48G buffers... Runnng multiple WAS instances in a single virtual machine is normally not a good idea. You make it very hard for z/VM to understand the true resource requirements and it gets impossible to allocate the right amount of resources to each application. The "normally" is because WAS is still having trouble to manage their idle load and thus complicate your configuration, but I'm trying hard to make them do something about that. Rob -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/
