[SOLVED] Zfs Tuning high memory

[Ronald Faraj]

Hi,

I installed Proxmox 4 with raid 1 in ZFS

We have just 7 VMs (4 Linux on Centos7 and 3 Windows) with 20 G total in all of them.

In Proxmox UI we can see 73 GB used in node
RAM usage
58.66% (73.80 GiB of 125.81 GiB)


You can recommend best way for tuning the Zfs memory with Proxmox? I think that's the reason for the memory problem or do you have any other suggestions?

Thanks and regards.

 

[Ronald Faraj]

I have tried reducing the memory cache of Zfs. This can done creating the follow file:

root@virtual:~# cat /etc/modprobe.d/zfs.conf
options zfs zfs_arc_min=5368709120
options zfs zfs_arc_max=10737418240

min 5 G - Max 10

Look this post: https://ispire.me/if-zfs-is-eating-your-memory/

At the moment i can see you memory usage, i'll test this configuration.

regards

 

[tschanness]

While it might well be the reason ZFS is designed that way. You could "tune" to use less RAM but you _should_ not. If you want to do it anyways the ZFS tuning works the same on Proxmox as it does on other Linux systems.

J.

 

[LnxBil]

I still don't get your "problem".

I really like to have almost no RAM free, because that says that a lot of stuff is cached in memory and does not have to be read from the terribly slow disk. Maybe you should familiarize yourself with Linux and its ram usage: http://www.linuxatemyram.com/

 

[Ronald Faraj]

Maybe do not explain me well, proxmox and storage are on the same server, that causes me to run out of memory for the VMs. The only solution I see is to migrate the storage to another server. This is not how Linux manages memory, it is how Zfs manages memory to improve read / write performance

Thank you for your answers.

 

[LnxBil]

This is not how Linux manages memory, it is how Zfs manages memory to improve read / write performance

For non-ZFS there is normal filesystem cache, for ZFS there is the ARC and both will be emptied if you run out of memory. It is still very bad if you server has free (as in "real" free memory).