[ovirt-users] Using zRam with oVirt Nodes

[Fernando Frediani]

All nodes I user zSwap (or Swap in zRam) I do have also some swap space 
in disk with lower priority which when/if gets used means something warning.

Overall the usage of zSwap helps a lot to increase the density of a Host 
at the cost of CPU which in most cases is more idle than memory or storage

Fernando


On 30/12/2016 21:47, Pavel Gashev wrote:
> I enable zSwap on my oVirt nodes by default. However zSwap is not the same thing as zRam. The purpose of zSwap is decreasing I/O by compressing swap itself. zSwap uses some ram for compressed swap, but it doesn’t try to keep a page in memory if it can’t be compressed.
>
> I find using of zRam without swap too risky. You don’t know when OOM killer start its job.
>
> -----Original Message-----
> From: <users-bounces at ovirt.org> on behalf of Fernando Frediani <fernando.frediani at upx.com.br>
> Date: Friday 30 December 2016 at 20:06
> To: "users at ovirt.org" <users at ovirt.org>
> Subject: [ovirt-users] Using zRam with oVirt Nodes
>
> Hello folks.
>
> On simple libvirt/KVM hosts in order to improve RAM usage and avoid swap
> to disk I use zRam with swap to RAM technique. So create half of amount
> of host memory in zRam disk divided by the number of CPU cores. Works
> pretty well.
>
> Has anyone tried it with oVirt Nodes or even has it been considered as a
> feature to simply turn on/off ?
>
> Thanks
> Fernando
>
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