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Swap size high how to tell if we have a memory issue

Hi All,

I have a couple of questions about swap. We are using CentOS 5 and I'm seeing a few servers that have swap in excess of 10GB. In the past (and not sure if it is still true) we were able to tell if we had a lack of memory from this exceeding say 5-8GB.

So now I am seeing a server which has 64GB of memory and is swapping 12GB. The only thing that this server is setup for is an Oracle database server. We have the SGA(35GB) and PGA(25GB) combined 60GB. There are no processes at the moment running so what could be consuming all of the swap? Top is showing when I filter from swap that it is the Oracle processes.

On another server that has 32GB of memory the swap is around 1.5GB. The SGA(17GB) and PGA(11GB) combined are 28GB.

I have another 40GB VM server running kvm. I have two VMs, one running 10GB and the other 24GB with 40GB of memory on the server. It had around 12GB of swap. When I shut down the 24GB VM, the swapped dropped 8GB.

How can I check if I really have an issue with memory allocation to prevent issues from happening in the future?

Thanks for your time.
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Swap space can be in use for many reasons, so it doesn't necessarily means memory shortage. Look at the swap in/out activity to see if there is in fact swapping going on. You can use sar -W, for example.
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