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From "Leon Rosenberg" <>
Subject Re: tomcat memory allocation
Date Tue, 11 Jul 2006 13:13:55 GMT
I think you need 64bit jvm.
With 32bit vm 1.5 is pretty much the limit.
With 64 bit sky is your limit :-)


On 7/11/06, Speulman, Elly <> wrote:
> We have a /3GB switch (and the /PAE switch active), but the allocation limit
> is still 1500m.
> We were using j2sdk-1_4_2_03 and tomcat-5.0.19. I have now tried the
> combination jdk-1_5_0_06 and tomcat-5.5..17.exe with the same poor result.
> So something seems to be wrong but what is it?
> Rg.
> Elly
> -----Oorspronkelijk bericht-----
> Van: Mark Thomas []
> Verzonden: donderdag 6 juli 2006 3:25
> Aan: Tomcat Users List
> Onderwerp: Re: tomcat memory allocation
> Speulman, Elly wrote:
> > Hi,
> >
> > Is there anyone out there who has been able to configure more than 1550M
> for
> > Tomcat 5.0 on a Windows advanced server installation. The server has a
> total
> > of 4Gb of memory. We are just not able to cross a border.
> > Config of Tomcat memory takes place via the Tomcat configuration buttons.
> > Perhaps someone even has a solution?
> This is a windows limitation. Do a Google for /3GB and /PAE boot.ini
> switches. The maximum memory varies by version (2003 is 32GB, 2003 SP1
> is 64GB) and I can't remember them all but the short (actually quite
> long) answer is:
> The default windows installation has a maximum of 4GB RAM. Of this,
> the kernel is allocated 2GB and user processes the rest with a maximum
> per process of 2GB (although in practice is is usually around 1.6GB).
> The /PAE switch should make all the physical memory in your machine
> visible to windows up to the maximum supported by your OS and SP
> versions. However, 2GB is still allocated to the kernel and user
> process are still limited to 2GB (really 1.6GB) each.
> The /3GB switch reduces the kernel allocation to 1GB and makes 3GB
> (really about 2.6GB) available per user process but total memory is
> still limited to 4GB.
> Using both /PAE and /3GB together gets 'interesting'. kernel memory is
> reduced to 1GB, user processes limited to 3GB per process and total
> memory is the smallest of physical memory, OS/SP maximum and 16GB.
> Note the 16GB upper limit. This caught me out recently on a 48GB
> windows box.
> On your box, I would use the /3GB switch but be aware of the 16GB
> upper limit for total system memory in this case.
> HTH,
> Mark
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