How do I size my  WebSphere severs? Dmgr, NA and Appsevers.

I am using IBM's GCMV tool but I do not  completely understand.  We need to run performance tests, analyze the results and size out JVMs.

Is there a way for me to run performance tests myself alone with out actually including appteam ( I  believe this question is vague,  I apologize, I just wanted to put it here)

How do I run perfromance tests on dmgr and Nodeagents and size tem appropriately?

Thanks in Advance.

Sizing, and tuning, of the application servers is highly dependant on the application deployed to the JVM / cluster.  Due to this dependancy, you will need the application deployed to the application servers in order to tune it appropriately.

The DMGR and NodeAgent, normally do not need tuned.  These two services are for administration (DMGR) and consolidated communication (NodeAgent.)  As such, they are not as "active" when compared to an application server running a user applciation.

As a rule of thumb, I typically start with the defaults for WebSphere ND and adjust if needed (which for the DMGR and NodeAgents I've not needed to modify.)  I believe the DMGR starts with 512MB, growing to 1.5GB for the heap, while the NodeAgents typically hover around 256MB for the Heap.

Honestly, there's not much tuning you need to do on the administrative processes for most environments. 

Thanks Erik.

I have seen more than few out of memory errors in the dmgr and nodeagent logs, hence was my concern.

Gues I will have to just try using diffent settings.

The default for all the JVM appears to be 256mb at least on Version 7

 

I have seen out of memory issue with the default dmgr setting especially if a lot of people are logging on doing different things and or when you have certain portions of Performance monitoring enabled.

As mentioned sizing depends on what your application need

For the nodeagent I've kept as it 256mb For the DMGR i bump up to a range of  512 to 1024

1 If there is no reference point to go by I usually start with 1024/1024 Enable Verbose GC

2. see what it's application only keeps heap occupancy  for example app starts and jumps to 700mb GC is trigger goes up and down a few time BUT eventually it stablizes where it averages 256 or less at rest.. 1024 imho is a good start if greater than 256 then I take that number lets say 512 and divide by .25 as in 512/.25 with gives 2048/2048 for my intial start. i try to keep the numbers divisable by 256 and alway round up so 360/.25 = 1440 1440/256 = 5.625 up it to 6 so new size is 1536/1536

3. keep Verbose GC enabled let the testing begin..and try not to recycle application or jvm so you can capture its highs and low heap use after gc over several days or weeks.

If the low is 180mb of heap use after gc and the high is 630mb I either set jvm min to 180x2=360 round up in  next 256 increments so xms is 512 do the same for 630mb 630x2=1260 rounded up to next 256 so xmx is 1280 or set both the high so its 1280/1280

1280 in this case is slightly more than absolutely needed BUT it allows room for the unexpected 25-30% increase.. Prestine perfect world never changing numbers would be 256/900 or lets say 256/1024 or 1024/1024  this keeps the standard 70% rule