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ARC size tunable set incorrectly

Description

When I set loader tunable vfs.zfs.arc_max to value "30G" (without quotes) (see screenshot), upon reboot the arc_summary command shows a "Max size (high water)" of only 10GiB. Variables arc.max and arc_max are shown with a consistent value in bytes. Setting the ARC size to the correct values seems seems only possible by issying the command: sysctl vfs.zfs.arc_max="32212254720"

This is happening on Truenas Core 12.0-U4.1. This used to work properly in FreeNAS 11.3-U5.

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Haje Korth 
September 10, 2021 at 4:20 PM

 I have reported this issue for TrueNAS Core and was hoping for a fix. I see above that this change has only been adopted for SCALE. Is this correct?

Bug Clerk 
September 6, 2021 at 6:05 PM

Haje Korth 
September 5, 2021 at 11:41 AM
(edited)

I confirm that I power off the VMs by command because I was not sure whether turning off the VM via GUI switch gives a clean shutdown. I tried turning of a VM from the GUI and I confirm that in this case the ARC size is properly increased after VM shutdown by the amount of memory used by the VM. So the flaw seems to be that the middleware does not recognize when a VM is shutdown by command. I would still consider this a bug.

As for the change in logic to use free memory instead of reducing ARC size, I have submitted suggestion NAS-112188.

 

Waqar 
September 1, 2021 at 12:09 PM

your suggestion would be change of behavior to how this section is already being handled or how existing users know this is working right now. Can you please create a suggestion ticket for that outlining how you think memory should be controlled wrt VMs ? ( this would include how you think the system should determine that the system has sufficient RAM wrt workloads that we don't change ARC )

About the test which showed memory wasn't being reclaimed after shutting down the VM, i think i know what might be the cause for that - can you confirm please if you stopped the VM from the VM itself and not the UI ? Thank you

Haje Korth 
August 31, 2021 at 3:07 PM

Is there an update on this issue? Anything else I can do to get this out of the "Blocked" status?

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Katalon Platform

Created July 20, 2021 at 11:48 PM
Updated July 28, 2022 at 1:50 PM
Resolved September 10, 2021 at 2:57 AM