To set a persistent arc maximum, you need to create a new file
/etc/zfs/zsysctl.conf. An example file is installed at
/etc/zfs/zsysctl.conf in your favorite text editor, and add a line like this:
This would limit the arc max to 11GB (see table below).
You may also wish to set the arc meta limit explicitly. The default is 1/4 of the arc max, but for some workloads 3/4 may be more appropriate. Setting 3/4 of the arc max above:
For additional information, please see Performance.