ZFS: Disabling ARC?

[Quartz]

> If you are really worried about the ARC hogging RAM, then set a cap.
> The kernel tunables here are:

I'm not worried about it hogging ram per se, but rather I'm a little 
confused about where and when it helps, where it's useless or 
detrimental (if ever), and consequently I don't really know when I 
should tune it or what to tune it *to*.

Basically, my question is the subject line of this thread: is there ever 
a reason to attempt to disable ARC, and what would that situation 
probably look like?


> Please note that I have never seen a _panic_ due to ARC RAM issues, I
> have had systems starved for RAM for periods and processes (VMs) get
> very angry, but the system as a whole usually recovers. I then
> restart the processes that got angry.

I didn't mean panics specifically due to ARC, but that in the process of 
reading various threads about memory related panics and ARC memory 
issues (separately) I realized that I wasn't really clear about memory 
management on FreeBSD and how ARC interacted there.