Options for zfs inside a VM backed by zfs on the host

[Vick Khera]

On Thu, Aug 27, 2015 at 6:10 AM, Marie <marieheleneka at gmail.com> wrote:

> I've tried this in the past, and found the worst performance penalty was
> with ARC disabled in guest. I tried with ARC enabled on host and guest,
> only on host, only on guest. There was a significant performance penalty
> with either ARC disabled.
>
> I'd still recommend to experiment with it on your own to see if the hit is
> acceptable or not.
>

Thanks for all the replies. I'm going with a small-ish ARC on the VMs
(about ¼ the allocated RAM as max, and very small amount for min) and
letting the host have its substantial ARC.

Since I'm running with compression=lz4 on the guest, I ended up setting
compression=none on the host for the backing volumes. After some testing I
found I was getting no compression on the backing volumes, so why waste the
CPU overhead trying.