Truenas increase RAM cache?

I have a strange question, opposite of most Truenas RAM cache questions…

Is there a way to tell Truenas to use more RAM for ZFS cache? I just added a pile of RAM to my lab server, and noticed it is only using 2.xGB of cache leaving around 88GB free. The RAM was cheap so I just went ahead and installed it to see if I could get a little better performance out of the slow system, especially when I’m doing Windows updates.

It will allocate on its own. The more you use the nas the more cache it will store. No configuration required.

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TrueNAS Core will do it on it’s own, TrueNAS scale follows the Linux settings of only using 50% of memory. You can set the max via the command line but it will clear with a reboot so perhaps a startup cron setting using this command:

echo 53687091200 >> /sys/module/zfs/parameters/zfs_arc_max

That set’s it to max our ARC cahce at 50G