installed system memory differs from mounted (available) memory
 

Hello Everyone,

I'm on a strange problem. I installed Debian on a Desktop computer and noticed that the system was quite slow, especially with OpenOffice and Opera running at the same time.

lshw tells me that I have 512 MB of RAM installed.
vmstat/dstat tells me that the total amount of RAM (available) is only 187 MB. The swap is as it should be 956 MB available and mounted.

Could anyone please advise on how to "find" and mount the rest of the RAM supposed to be installed on this computer?

Regards,
Liviu

=============== Commands output ===================
# lshw
*-memory
description: System Memory
physical id: 19
slot: System board or motherboard
size: 512MB
*-bank:0
description: DIMM
product: None
vendor: None
physical id: 0
serial: None
slot: A0
size: 512MB
width: 64 bits
*-bank:1
description: DIMM [empty]
product: None
vendor: None
physical id: 1
serial: None
slot: A1
width: 64 bits

$ vmstat -s -S M
187 M total memory
180 M used memory
129 M active memory
36 M inactive memory
7 M free memory
1 M buffer memory
32 M swap cache
956 M total swap
173 M used swap
783 M free swap
9665 non-nice user cpu ticks
0 nice user cpu ticks
1802 system cpu ticks
218740 idle cpu ticks
4890 IO-wait cpu ticks
96 IRQ cpu ticks
61 softirq cpu ticks
0 stolen cpu ticks
229943 pages paged in
222184 pages paged out
14153 pages swapped in
45258 pages swapped out
717158 interrupts
952759 CPU context switches
1186663403 boot time
4434 forks

What does the free command show:

$ free

Same story:

# free
total used free shared buffers cached
Mem: 192168 189016 3152 0 828 69836
-/+ buffers/cache: 118352 73816
Swap: 979924 159344 820580

I'm stumped. The only thing I can suggest is to make sure it's just not some error in the monitoring app, i.e. your system is really seeing only 187MB of ram. From what you posted, it appears that your system is truly seeing just the 187MB of ram.

I don't know that much about the stock debian kernel which I assume you are running. However, IIRC the linux kernel has the ability to check ram for errors and mark any bad sectors on the ram stick. The bad sectors will not be used on any subsequent boot and that may result in the reported ram being less than the installed ram. That may be something to look into.

You might also thoroughly check your ram with memtest. Let it run overnight and see if any errors are reported. I also assume you are not overclocking or anything like that.

Does the memory show up at its full capacity in your BIOS/startup post screen? If not then you may need to flash the BIOS to a newer version you might also want to check to see if your motherboard (what make/model is it anyways?) supports 521mb sticks. One thing you can try is when you get to the grub boot screen hit the c key then boot use the grub command prompt and add the mem=512M to the command when booting the machine. To do this look at the first entry/the one that boot Debian if not the first in your /boot/grub/menu.lst file like this below.

Now once you have used the c key to get to the command prompt you would need these commands to boot your system using my entry above as a template changing to yours when you do it.

Now hopefully it will see and use all your memory if this works then edit the line in the menu.lst and add the mem=512M to it to have it used on every boot.

Thank you all for answering.

Since I am new to this computer, I was relying only on the linux hardware detection tools. Checking the hardware with Aida 32 on Windows, it actually has installed 192 MB of RAM only. My guess is that this is some bug in lshw, which shows the memory capable of supporting instead of the actual installed memory.