ZFS 10% default arc_max on new installs

[entilza]

Hi can this be clarified:

• The arc_max parameter for installations on ZFS can now be set in the Advanced Options. If not explicitly set by the user, it is set to a value targeting 10% of system memory instead of 50%, which is a better fit for a virtualization workload (issue 4829).
• https://pve.proxmox.com/wiki/Roadmap#Proxmox_VE_8.4

So this works on a new install I see this work great I see:

# cat /etc/modprobe.d/zfs.conf
options zfs zfs_arc_max=12977176576

Shows 12GB of my 128GB perfect.

However I have older nodes I upgraded to 8.4 that don't have this file and I added it and it does nothing. How can I add this same functionality to my older nodes?

Thanks.

 

[leesteken]

However I have older nodes I upgraded to 8.4 that don't have this file and I added it and it does nothing. How can I add this same functionality to my older nodes?

You need to run update-initramfs -u and reboot (after adding the file with the desired size). See the manual: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#sysadmin_zfs_limit_memory_usage

 

[Impact]

Also see here.

 

[entilza]

Perfect! Thank you for the quick response this did it.

 

[SInisterPisces]

Hi can this be clarified:

• The arc_max parameter for installations on ZFS can now be set in the Advanced Options. If not explicitly set by the user, it is set to a value targeting 10% of system memory instead of 50%, which is a better fit for a virtualization workload (issue 4829).
• https://pve.proxmox.com/wiki/Roadmap#Proxmox_VE_8.4

So this works on a new install I see this work great I see:
[deletia]

Thanks for bringing this up. Glad you got it working.

Just to clarify for anyone who thought they were missing something in the PVE GUI (hi, it me), the Advanced Options mentioned above are those settable during the initial install.

ZFS ARC size does not have an adjustable setting within the PVE GUI yet.