1By default ZFS Arc Cache take 50% of Memory
Using following config you can limit
Create a new file
nano /etc/modprobe.d/zfs.conf
Add following Line. 8589934592= 8GB
options zfs zfs_arc_max=8589934592
If your root file system is ZFS you must update your initramfs every time this value changes:
Use following command to update
update-initramfs -u
Reboot System
Check new limit using following command
# cat /sys/module/zfs/parameters/zfs_arc_max 8589934592