# Too much ram?

## draconyster

i have like 16Gb Ram, and whenever too much of it is used my system freezes. I tried to use memtester (not memtest) and whenever it allocates all RAM the server freezes...

RAM is 100% ok i changed it 3 times.

Later ive  read of paging problems with so much RAM, and that on  BSD it could be solved by NKMEMEPAGES parameter in sysctl.

How do i fix it in gentoo?

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## John R. Graham

You can never have too much RAM.    :Wink:    First, let's check to see if you have all of the required kernel parameters set.  Make sure that 

```
  -> Processor type and features                                                                            

    -> High Memory Support (<choice> [=y])
```

is set to 64GB in your kernel configuration.  Without that, you're not actually using all 16GiB.

- John

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## der.gecko

@john_r_graham: you're right, but even without his system shouldn't freeze...

@draconyster: check the settings in the bios, perhaps you've accidentally overclocked your ram or cpu...

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## draconyster

nope, bios is  fine. havent even touched it  :Smile: 

Well red hat failed the ame way too  :Sad: 

Could it be im having same trouble as bsd with that paging?

How else can i check?

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## der.gecko

if you haven't touched the bios, do it now... if you are unsure, use the setting "load optimized defaults" (or similar). sometimes a bios can make a mistake in detecting hardwarespecs... with the factory defaults loaded at next startup you have a higher chance of getting correct results. as far as it concerns the os i honestly don't know what could cause the probelm. i would try to boot from a knoppix livecd, since it has one of the best hardware detecting routines.

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## John R. Graham

You could also try running memtest from the install CD.  Obvious from your RedHat test that it's not a Gentoo-specific issue.

- John

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## draconyster

i can only access serial console, so i cant run a memtest86.....

But RAM is really fine

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## mrbig4545

Have you tried taking some out and finding out how much ram makes it freeze? Does dmesg give any errors which could be related?i had a similar problem, although was only 3gb involved, which was fixed with a bios update.

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## draconyster

 *john_r_graham wrote:*   

> You can never have too much RAM.      First, let's check to see if you have all of the required kernel parameters set.  Make sure that 
> 
> ```
>   -> Processor type and features                                                                            
> 
> ...

 

i dont see that config line in 2.6.20 kernel

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## John R. Graham

It's there.  I'm running a kernel based on 2.6.20-gentoo-r8 (Reiser4 patches applied).

- John

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## x22

 *john_r_graham wrote:*   

> It's there.  I'm running a kernel based on 2.6.20-gentoo-r8 (Reiser4 patches applied).
> 
> 

 

That option exists on i386 but not on amd64.

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## John R. Graham

Ah.  Many thanks.

- John

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## draconyster

well i have 8 double corre opterons, so i dont think it s going to be in my config  :Sad: 

i tried raising limt with ulimit, this somehow helped, but there still are crashes

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## Akkara

Try underclocking everything 10% or so just to be sure it is not a hardware problem.  Especially driving so much ram.  I've seen some RAM *barely* work at their spec by themselves, but pair them up with another module the system fails.  Sometimes it'll even boot and pass memtest, but looping repeated compiles of the kernel results in a segfault.

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## davidgurvich

Have you tried using less physical ram?  Might be a motherboard problem.

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## draconyster

you see its a dedicated server  :Sad:  i cant just pull out RAM, or access BIOS.... It would require a ticket, and take a week or so, and the problem may not be there.

I raised ulimit max locked memory to unlimited and now memtester is finally able to lok that memory.

Then it says: Stuck address: 0

and the counter doesnt go on, its just 0 (perhaps its just taking that long because i test a lot of RAM), and then the system just freezes in like 20 seconds

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