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952799 wrote:Why are you obliged to run the 32-bit version of 11gR2? You are wasting a lot of that server by installing a 32-bit operating system and a 32-bit database, even with a PAE kernel.
I have a new database server with 128 GB of RAM. On this server I'm obliged to install 11gR2 32 bit, so to receive full support I'm obliged also to install a 32bit OEL.
If I use the el5 kernel with OEL 5.7 I can see only 64 GB of RAM, but I would like to install UEK . I didn't find any PAE unbreakable kernel, how can I modify UEK to see 64 GB of RAM ?You can't. You should use 64-bit Oracle Linux with the UEK to see all 128GB of RAM.
Installing Linux x86_64 will probably be your only option if you use RHEL or Oracle Linux 5 or later.
Under Enterprise Linux 5 there are kernel limitations that allow you to use only up to 16 GB reliably before you can run into lowmem starvation issues. The situation was different with EL3 and 4 and the hugemem kernel, which provided more lowmem space to manage the amount of physical RAM.
Red Hat Enterprise Linux 5/ Oracle Linux 5 on 32-bit does not have the hugemem kernel. It supports only the 3GB user process/ 1GB kernel split. It has a PAE kernel that supports systems with more than 4GB of RAM and reliably upto 16GB. Since this has a 3GB/1GB kernel split, the system may run out of lowmem if the system's load consumes lots of lowmem. There is no equivalent kernel for hugemem in Enterprise Linux 5 and one is recommended to either use Enterprise Linux 4 with hugemem or go for 64-bit.