ZFS on FreeBSD 11.3 slower than 10.4

[Ronald Klop]

On Sat, 23 May 2020 21:44:03 +0200, Miroslav Lachman <000.fbsd at quip.cz>  
wrote:

> I upgraded my old desktop computer few month ago from old 10.4 based  
> PC-BSD to stock FreeBSD 11.3. It uses single 2TB HDD 7200rpm.
> My problem is that upgraded version is really slow and some desktop  
> applications are very lagging (playing multimedia is interrupted for a  
> fraction of seconds) when there is heavy filesystem activity.
>
> I am using zfsnap2 for taking snapshots periodically and when there is  
> enough snapshots zfs destroy is called. In this time the user experience  
> is terrible. Starting new application like browser or even something  
> much smaller takes minutes. The old version based on FreeBSD 10.4  
> behaves much better. I used the old version for years and never have  
> problems with interrupted multimedia playback.
>
> Are there some sysctls to tune to get better desktop interactivity in  
> heavy filesystem operations like zfs destroy, pkg check or other "find"  
> periodic scripts?
>
> Kind regards
> Miroslav Lachman


How full is the disk? ZFS has poor performance if the disk becomes full.
What is in /etc/sysctl.conf and /boot/loader.conf?
And did you try to boot 12.1 and did it have the same behavious?

Regards,
Ronald.