topic Re: more than 4gb in Operating System - Linux

more than 4gb

Joaquin Mejias Gallego — Sun, 01 Jun 2008 17:49:41 GMT

I have a server(proliant)with 5,5GB RAM But my operating system (debian 4.0) only recognized 3,5GB.
How to make my Operating system work with more than 4gb ram

Re: more than 4gb

Salah BOUFARGUINE — Mon, 02 Jun 2008 11:03:08 GMT

Hello
You need an OS 64b
regards

Re: more than 4gb

Liviu I. — Mon, 02 Jun 2008 11:06:09 GMT

You need a 64 bit processor and a 64 bit Linux.

Re: more than 4gb

Srimalik — Mon, 02 Jun 2008 11:40:48 GMT

You need a 32 bit kernel with hugemem enabled(hugemem kernel).

You can use 16GB RAM on a 32bit hugemem kernel

Re: more than 4gb

Joaquin Mejias Gallego — Mon, 02 Jun 2008 11:46:31 GMT

Thanks

I installed 2.6.18-6-686-bigmem

Re: more than 4gb

Srimalik — Mon, 02 Jun 2008 11:50:08 GMT

did bigmem help?

BTW, I am not sure about the memory limit in hugemem kernel, but Its more than 4GB for sure.

Re: more than 4gb

Matti_Kurkela — Mon, 02 Jun 2008 11:52:41 GMT

Even a 32-bit Linux system can handle more than 4GB RAM if both the hardware and the OS support PAE (Physical Address Extension).

In Linux terms, this means you must have kernel that is configured to support your CPU type and has the CONFIG_HIGHMEM64G option set. Your current kernel is apparently using only the CONFIG_HIGHMEM4G option, which is not enough.

However, the use of PAE on a 32-bit system is not as efficient as running a true 64-bit system. Any I/O operations to memory areas above the 4GB limit must use "bounce buffers".

PAE won't allow you to bypass the fundamental 32-bit limit: you can have several programs with up to 4G of data each if you have enough memory, but no single program can access more than 4 GB of memory.

You should seriously consider installing a 64-bit version of the Debian Linux: it is backwards compatible with 32-bit programs, so you can still run 32-bit programs on a 64-bit OS. If you need your application to access more than 4GB of memory, you'll definitely need a 64-bit application.

MK

Re: more than 4gb

Joaquin Mejias Gallego — Mon, 02 Jun 2008 11:58:34 GMT

with kernel bigmen now the OS works with 4GB.

My proliant shows when starting only 4GB initialized but I'm sure that the server has 5,5GB (4x1gb and 3x512)

Sorry by mi english, I'm from spain.

Re: more than 4gb

Joaquin Mejias Gallego — Mon, 02 Jun 2008 13:03:06 GMT

I don`t find hugemem kernel in debian.org only bigmem
dmesg:
Memory: 4147696k/4718592k available (1542k kernel code, 45292k reserved, 587k data, 196k init, 3276776k highmem)
Freeing initrd memory: 4881k freed
Freeing unused kernel memory: 196k freed

cat /proc/meminfo
cat /proc/meminfo
MemTotal: 4153680 kB

Re: more than 4gb

Heironimus — Mon, 02 Jun 2008 15:06:06 GMT

I don't think any of my Proliants can use 7 memory modules. Are you sure that's a supported configuration? During the POST how much memory does the server report?

bigmem is the correct variant to use in Debian for 4-64GB. hugemem is a Red Hat thing, on current RH variants you have to use the hugemem kernel for 16-64GB.