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RHEL 5.2 not recognizing memory beyond 4GB

 
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Super Advisor

RHEL 5.2 not recognizing memory beyond 4GB

Hi,

A rx2660 has 8GB of Physical memory installed, but RHEL 5.2 is showing only 4GB.

Can anyone pls help?

Thanks in advance
10 REPLIES 10
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Honored Contributor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Does the kernel you're using have CONFIG_HIGHMEM64G enabled?

Goran
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Super Advisor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Hi Goran,

Pls guide me on how to check this & confirm
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Honored Contributor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Hello.

Well I suppose you're using the kernel from RH so grep for it in its config file in /boot.

Perhaps you just need proper kernel package installed, i.e. something similar to "bigmem" kernels in Debian.

Regards,
Goran
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Exalted Contributor
Solution

Re: RHEL 5.2 not recognizing memory beyond 4GB

Shalom,

The only version of Red Hat that works on an Itanium Server is RHEL for IA-64.

It should without any modification, being pure 64 bit, memory beyond 4 GB.

There is no hugemem or special kernel settings for IA-64 Red Hat.

Please post the following output for further diagnosis:

free

vmstat

Please confirm on the hardware side that all 8 GB of ram are working.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
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Honored Contributor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Doh, so much for knowing what rx2660 is ;)
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Super Advisor

Re: RHEL 5.2 not recognizing memory beyond 4GB

The issue is resolved. We were using the xen kernel. Actually, during the installation, we did not deselect "Virtualization" and that had left our the ia64 kernel.

The ia64 kernel is showing 8GB memory now.

One more unique thing was observed - the xen kernel does not show the service startups during booting, and, we couldn't get into the Single-user mode with the xen kernel.

Thanks all.
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Super Advisor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Can anyone lend me the procedure to enable CONFIG_HIGHMEM64G in a kernel (where it is not enabled)?

Thanks again!
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Honored Contributor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Hi.

I have mislead you with CONFIG_HIGHMEM64G option because I had no idea this is an Itanium machine. Sorry about that.

This option is only relevant for 32bit kernels running on x86.

Regards,
Goran
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Super Advisor

Re: RHEL 5.2 not recognizing memory beyond 4GB

Hi Goran,

It was not clear on my part about the architecture.

But, it very important to know how to configure the CONFIG_HIGHMEM64G option even in case of 32bit kernels running on x86. Can you provide me some leads with that.

Thanks!