CPU recommendations for Truenas in a VM

[bullerwins]

Hi!

I’m going to build a Truenas, not sure about core or scale yet, probably core for the better performance at the moment as it’s only going to be used as storage. Inside an Unraid VM, I prefer Unraid for stuff like plex, vpn, torrent containers… and run truenas as a VM inside Unraid with some HDDs and an SSD pass through’d.
I have a Ryzen 3900x, 32gb of 3200mhz ram. My question is about CPU cores to pass though. The official documentation doesn’t go in detail about how many cores would be optimal. RAM I’m going to assign as much as possible not needed for Unraid. But not sure about CPU cores for optimal performance.
I have x2 14tb, x3 8tb and a 500gb nvme for cache l2arc.
My 3900x has a total of 24 vcores. How many would you assign? I have a 10gbit network nic

Many thanks in advance. Just starting to the my feet wet with truenas.

 

[jgreco]

You follow the typical hypervisor practice of starting small and then only adding if needed. Two is suggested because ZFS and userland can both be busy on CPU-intensive stuff. You're likely to end up wanting 3 or 4 in the end.

You can skip the L2ARC. With 32GB of RAM in the system, even if you allocate 24GB to TrueNAS, you're really quite small. We normally don't recommend L2ARC until system RAM (ARC) is 64GB+, though you might see mild benefits at 32GB. L2ARC should be no more than 5x-10x your TrueNAS's system memory size in any case.

Make sure you've read

"Absolutely must virtualize FreeNAS!" ... a guide to not completely losing your data.

[---- 2018/02/27: This is still as relevant as ever. As PCIe-Passthru has matured, fewer problems are reported. I've updated some specific things known to be problematic ----] [---- 2014/12/24: Note, there is another post discussing how to deploy a small FreeNAS VM instance for basic file...

www.truenas.com

 

[bullerwins]

That was really helpful, and the link too. Thanks a lot.
I’ll start low and work my way up to test performance differences. Yes around 24GB of ram is what I’m going to use. I might test the ssd anyways as I don’t have any use for it

I also have an old intel i7 920 and a motherboard. Would that bare metal be better? I’d have to check the ram though as I think I only have 16gb and it’s DDR3 (does ddr3 matter for l1arc?)

 

[jgreco]

Bare metal is generally better. Your network is infinitely slower than even DDR2 memory, so a dedicated system with 16GB of DDR3 is probably a better choice than a virtualized system with DDR4.

 

[bullerwins]

Thanks! That’s what I though. I’m still learning about truenas cache system. Using ram as cache seems like it’s never going to be a bottleneck.