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I put 4 gigs of RAM into a server, but when I look at the command line why does it say I have only 3462960k RAM?

[root@localhost ~]# cat /proc/meminfo 
MemTotal:        3462960 kB

[root@localhost ~]# free
             total       
Mem:       3462960  

[root@localhost ~]# top
Mem:   3462960k total...
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Perhaps MemTotal doesn't mean what you think it does redhat.com/advice/tips/meminfo.html or you MB isn't seeing all the RAM. –  Iain Jun 15 '13 at 5:31
4  
@TomTom It's probably a phone.... –  Michael Hampton Jun 15 '13 at 5:53
2  
Coming? The phone in my pocket is a quad core phone. :) –  mrdenny Jun 15 '13 at 6:11
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Sarcasm? @TomTom I think you might misunderstand Michael; your phone is the stuff of legends with the rest of us regulars :-) –  RobM Jun 15 '13 at 8:14
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Hehe. I understand. It still has no 4gb ram though. Sadly - they do not make blade-phones.... could use some blade center full of wonderphones. –  TomTom Jun 15 '13 at 10:29

3 Answers 3

Because it is about 3.5GB that it is detecting, I suspect strongly that you have installed a 32-bit OS on the server. Some memory space is reserved for things like DMA.

You can verify this by using the uname -m command. If it says something like i686, it's a 32 bit OS; if it says x86_64 it's 64-bit.

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[root@localhost ~]# uname -m x86_64 –  davidjhp Jun 15 '13 at 15:35
1  
In that case, you have a hardware failure, or a lack of CPU or system board support for more than 3.5GB of RAM. Try updating the BIOS or EFI firmware perhaps, and failing that, swap out RAM modules. –  Falcon Momot Jun 15 '13 at 18:02

A better way

[root@localhost ~]# dmidecode --type 17 | grep Size
        Size: 2048 MB
        Size: 2048 MB
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That tells you how much RAM is physically installed in the server. Good to know, no doubt. But it fails to tell you how much the OS actually sees and uses (which is at least as important). –  Joachim Sauer Jun 15 '13 at 8:47
    
Bloody well important information for determining whether you have a hardware or a software problem though. –  Magellan Jun 15 '13 at 13:20

Sounds like you have a 32 bit operating system installed. Instead of re installing you could also look in to physical address extention

https://help.ubuntu.com/community/EnablingPAE

Gives help on Ubuntu. I'm sure you can find a similar method for the distro you have installed.

4gb should be plenty for your server unless you have large db or heavy io work planned

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Why the down vote ? –  exussum Jun 15 '13 at 13:50
    
Probably because your answer doesn't add much value over Falcon's answer –  mfinni Jul 25 '13 at 17:32
    
if its 32 bit enabling PAE will be a much easier process than reinstalling the entire OS –  exussum Jul 25 '13 at 17:41
    
1 - the OP did reply (admittedly after your answer) that it's a 64-bit OS. –  mfinni Jul 25 '13 at 17:43
    
2 - PAE helps with RAM above 4 GB. It won't help you get RAM that's stuck in the DMA hole on a 32-bit system, or not accessible due to hardware limitations on the board. –  mfinni Jul 25 '13 at 17:44

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