Why RHEV-H uses too much swap space?

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Hello,

We have a RHEV 3.2 installation.
Our RHEV-H, Hypervisor, uses too much swap space.
During the installation it recommends to create a partition of 210GB for swap.

Why it uses too much swap space.

Regards

Responses

Out of interest, how much physical RAM does the server have? 210G does sound a little exorbitant regardless.

The server has 398GB of RAM.

I agree with you, that is why I am asking why installator suggest this huge value.

The number seems correct for that amount of RAM as KVM uses SWAP for memory overcommit for guests.

There is some guidance on the how the swap configuration is calculated here:
http://linux.web.cern.ch/linux/scientific6/docs/rhel/Hypervisor_Deployment_Guide/#References_RHEL_6_RHEVH_Support_Limits

Specifically:
Overcommit allows the Red Hat Enterprise Virtualization environment to present more RAM to guests than is actually physically present. The default overcommit ratio is 0.5.
The recommended size of the swap partition can be determined by:
Multiplying the amount of system RAM by the expected overcommit ratio, and adding
2 GB of swap space for systems with 4 GB of RAM or less, or
4 GB of swap space for systems with between 4 GB and 16 GB of RAM, or
8 GB of swap space for systems with between 16 GB and 64 GB of RAM, or
16 GB of swap space for systems with between 64 GB and 256 GB of RAM.

So (398 * 0.5) + 16 = 215.. which is pretty close to what is being recommended.

Hi,

Sorry for delay.
Thank you all for answer this.

Now I understand better how it works, and why it uses this space.

Regards

Hello, What if we do not want the memory over commitment feature? Can we reduce to a minimal level? If so what could be the minimal value to be set?

Regards

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