[SOLVED] rhel not using all the ram

steinz · 02-06-2017, 08:49 AM

Hi,

I have a new rhel 7 64bit server with 132 gb rams.

#>free -m

total used free shared buff/cache available
Mem: 125G 15G 4.9G 43G 105G 66G
Swap: 16G 1.2M 16G

Shouldn't the used column be much higher than 15g if I have 132gb installed?

I have Oracle installed on the server

Thanks
Randy

jsbjsb001 · 02-06-2017, 09:11 AM

Quote:

Originally Posted by steinz

Hi,

I have a new rhel 7 64bit server with 132 gb rams.

#>free -m

total used free shared buff/cache available
Mem: 125G 15G 4.9G 43G 105G 66G
Swap: 16G 1.2M 16G

Shouldn't the used column be much higher than 15g if I have 132gb installed?

I have Oracle installed on the server

Thanks
Randy

From your output it looks like the OS is seeing all of the available memory in your server.

You have to remember that not all of your RAM will be available to the OS.

As your PC's hardware (on-board motherboard/integrated devices) will have some of the memory reserved and therefore that memory will be unavailable to the OS.

Edit: How busy is your server?

steinz · 02-06-2017, 09:56 AM

I thought Linux takes all the ram. But on my server, its only taking about 10% and the cache is taking the rest.

I am the only one using the server now.

hydrurga · 02-06-2017, 09:59 AM

Quote:

Originally Posted by steinz

I thought Linux takes all the ram. But on my server, its only taking about 10% and the cache is taking the rest.

I am the only one using the server now.

http://www.linuxatemyram.com/

steinz · 02-06-2017, 10:05 AM

thanks for the link, but I think that is the opposite of what I am asking.
The link seems to say its ok if linux seems to be using all the ram, I am asking why the os is not using all my ram.

Randy

suicidaleggroll · 02-06-2017, 10:14 AM

It's using almost all of it, what are you seeing that I'm not? You have 4.9G "free" and 105G being used for cache, what more do you want?

Maybe you're confused by the new format of free? It was changed in rhel 7 vs 6. I have two systems, each with 128 GB, one running CentOS 6 and the other on 7. Their usage is pretty similar, you can compare/contrast the output of free:

Code:

CentOS 6:
$ free -h
             total       used       free     shared    buffers     cached
Mem:          126G       107G        18G       6.3M       270M       105G
-/+ buffers/cache:       1.4G       124G
Swap:         3.9G         0B       3.9G

Code:

CentOS 7:
$ free -h
              total        used        free      shared  buff/cache   available
Mem:           125G        9.8G        6.8G        571M        109G        114G
Swap:          3.0G        992K        3.0G

Both systems are using ~105G for cache, but the output looks very different due to the new formatting.

steinz · 02-06-2017, 10:25 AM

I thought used would be much closer to total

something like:
total 125gb
used 120gb

suicidaleggroll · 02-06-2017, 10:26 AM

That was changed in RHEL 7, please see my post above.

steinz · 02-06-2017, 10:39 AM

you are right and very helpful. Thanks, I was getting the versions confused.

Randy