bhyve, Windows guest and trim support

[Peter Grehan]

Hi Andrea,

>> Thanks for this hint, I can now confirm this also works with virtio-blk
>> (applied Allan's patch to 12.1). REFER for the zvol backing my Windows
>> Server 2016 dropped from 315G to 72.5G.
> 
> Hmm...
> I applied the same patch and, still using virtio-blk, when trying to 
> retrim, Windows says "Optimize-Volume : The volume optimization 
> operation requested is not supported by the hardware backing the volume."
> Seems like the guest doesn't think TRIM support is available.
> Do I have to set anything?
> 
> I have the following in the machine config (I'm using vm-bhyve):
> disk0_type="virtio-blk"
> disk0_name="disk0"
> disk0_dev="zvol"
> disk0_opts="sectorsize=512"

  You may need a recent Windows viostor driver. A working configuration 
was reported in
     https://github.com/virtio-win/kvm-guest-drivers-windows/issues/392

later,

Peter.