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How much RAM is devoted to ZFS on MacOS?

PostPosted: Fri Apr 24, 2020 4:11 am
by randolph.kahle
I use my MacPro 5,1 heavily with applications that use a lot of RAM.

I am curious to learn if I can determine how much RAM is devoted to ZFS, in total, from my 48GB of physical RAM.

Is there a command I can execute from the command line to make this determination?

Re: How much RAM is devoted to ZFS on MacOS?

PostPosted: Fri Apr 24, 2020 11:57 am
by sean
It's a configuration thing. You'll want to make a /etc/zfs/zsysctl.conf file. There's a /etc/zfs/zsysctl.conf.example that you can use for reference. I don't know if it's a requirement, but I reboot after I make changes to that file.

Re: How much RAM is devoted to ZFS on MacOS?

PostPosted: Fri Apr 24, 2020 2:37 pm
by randolph.kahle
Thank you. Yes, I realize I can configure the memory.

What I am wondering is how can I check while running MacOS to see how much memory is currently allocated. I don't see anything in Activity monitor that corresponds to ZFS.

Re: How much RAM is devoted to ZFS on MacOS?

PostPosted: Fri Apr 24, 2020 7:39 pm
by tangles
The RAM used by ZFS will be represented by the kernel_task from memory… i.e. the kernel.

Reboot and note your initial value, then note how much it goes up as you use your datasets.

Not ideal I know.

There are some shell scripts that can show you from memory but I can't remember them off hand.

Someone else might know and chip in as I gotta remote setup a new router and ZFS box for a business in 2mins…

Such are the times..