Proxmox VE 4.4 100% SWAP Usage suddenly

[Mecanik]

Hello,

I really need some information/guidance why my Swap usage is suddenly 100% on one node and on the other one is 60% as well, suddenly...

Each node has the same set of 128 GB RAM, and running only Windows VM's.

Can someone please explain this to me ? Do I need to increase the swap size ? Why is KSM sharing working on one and on the other one not ?

Many thanks

 

[Rhinox]

Check "free" output. BTW, when your node is using swap, it needs more ram, not more swap...

 

[wolfgang]

Hi,

KSM do not work with AMD CPUs.
You are using more memory then you have this is the reason why you are swapping.

To increase the memory is no good way because when you start to swap the host will get very slow.

see
atop -mM

this will show you your memory usage.

atop must be installed before

 

[udo]

Hi,

KSM do not work with AMD CPUs.
You are using more memory then you have this is the reason why you are swapping.

To increase the memory is no good way because when you start to swap the host will get very slow.

see
atop -mM

this will show you your memory usage.

atop must be installed before

Hi,
I have seen that on one node also (I migrate some VMs to that spare node).
The strange thing was, that swapiness was set to 1 and there was RAM free (and many used for buffering). So normaly swap should not be used anyway!

The node has an Intel cpu...

Udo

 

[Mecanik]

Check "free" output. BTW, when your node is using swap, it needs more ram, not more swap...

I believe I have enough free RAM...

Hi,

KSM do not work with AMD CPUs.
You are using more memory then you have this is the reason why you are swapping.

To increase the memory is no good way because when you start to swap the host will get very slow.

see
atop -mM

this will show you your memory usage.

atop must be installed before

Well, both nodes have the same set of RAM and CPU, Intel Xeon... so KSM it`s working on one node, and on this one not.

Here is the output of the "problematic" node: https://i.imgur.com/RT32DVA.png ( free mem 38.1 G )

Here is the output of the "ok" node: https://i.imgur.com/3Io7hg7.png

Hi,
I have seen that on one node also (I migrate some VMs to that spare node).
The strange thing was, that swapiness was set to 1 and there was RAM free (and many used for buffering). So normaly swap should not be used anyway!

The node has an Intel cpu...

Udo

Well honestly, on this node where I have Swap 100%, I did not play around with it, just installed Proxmox 4.4 as normal, and started making VM's, while my other node where Swap is only 60% and KSM is working, I played around a lot ( if you remmeber I tried to setup clustering with running VM's and failed ), so what it going on I don't know....

 

[Rhinox]

I believe I have enough free RAM...

Then why using swap at all? The last time I have been using swap on my servers was some 5 or 6 years ago. ddr price is so low it is not problem to buy extra ram if needed...

 

[Mecanik]

Ok, this is really weird. One VM had the setting for RAM "Automatically allocate memory within this range" so yesterday I changed to "Use fixed size memory" and now the KSM started working, but the swap still looks bad:

Any suggestions ?