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need explanation linux command "free -m"

Hello,

I need more explanation of "free -m" linux command.

[root@xxxxxx /]# free -t -m
             total       used       free     shared    buffers     cached
Mem:          2026       1817        208          0        404       1035
-/+ buffers/cache:        377       1648
Swap:         2047         17       2030
Total:        4074       1835       2238

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As shown, we have 2G total, 1.8G used and 208 Megs free. Everybody will say that we need RAM, but
inline total : 4G total, 1.8G used, 2.2G free, so do I really need more memory ?

Is it good to use swap memory ?

We ask this question because the server is suddenly slow.

see this image ( Plesk shows 40% of memory used ) ?

thanks,

flubbard

Couple things. first off, free is only showing your usage as of the present time. Generally, you will have some things going to swap and that is not a problem. You would prefer active applications to not use swap instead of physical memory simply because there is no physical memory left...that would be bad.

That being said. If you are bumping up that close to physical ram, you probably would benefit from adding some.

As an aside, to find out more information on any linux command, look at the manual. You can access the manual by typing:
# man [application]

for example:
# man free

hth - flub

TobiasHolm

Hi!

I'd say you need more RAM. The swap is very slow compared to RAM. Try to use the 'top' command to see which processes that use your RAM. Sorting by memory usage (SHIFT-O n ENTER) will sort the top output by memory usage.

Regards, Tobias

dom_solariumdeparis

ASKER

Hello TobiasHolm,

see picture of the output of Top.
Do you see which processes that it use a lot of memory ?

regards,
free-m-2.JPG

TobiasHolm

You must use sudo to start top to see processes from all users.

sudo top

You can also use ps to see where the memory are used:
sudo ps aux

Regards, Tobias

madunix

If your machine uses a lot of swap then you should really think about tuning the system and then adding more memory

ASKER CERTIFIED SOLUTION

kareejb

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need explanation linux command &quot;free -m&quot;

need explanation linux command "free -m"