Re: [Qemu-discuss] Best Intel hardware for qemu

[Lars Bonnesen]

I want to pass local disks to a VM in order to run freenas or similar.

Regards, Lars.

On Wed, Apr 10, 2019, 20:20 Jakob Bohm <address@hidden> wrote:

> If you pass through the disk access to your SAN partitions as disk
> accesses to block devices (such as SAN client drivers) in the host
> machine, you don't need VFIO for that.  This can handle nearly
> unlimited number of virtual machines without running out of PCI
> slots in the host machine.  This is the equivalent of "passing
> through a SAN disk" in VMWare, but isn't artificially limited to
> SAN disks (for example, you can layer the Linux multipath drivers
> and/or the Linux disk encryption drivers between the virtual
> machine and the actual SAN).
>
> If you pass through the network access to your (iSCSI or NBD) SAN
> as network traffic via the general qemu/kvm network features, you
> don't need VFIO for that.  This can handle nearly unlimited number
> of virtual machines without running out of PCI slots in the host
> machine.  This is equivalent to using a "VMWare virtual switch".
>
> If you dedicate a physical SAN adapter (iSCSI, NBD, SAS or fibre
> channel) to each virtual machine and pass it through to that
> virtual machine, you need VFIO for that.  As on VMWare, this will
> limit you to one virtual machine for each PCI slot in the
> motherboard.
>
> If you dedicate a physical network adapter (NIC) to each individual
> virtual machine and pass it through to PCI drivers in that virtual
> machine, you need VFIO for that.  This too will limit you to one
> virtual machine for each PCI slot in the motherboard.
>
> As for passing through raw SCSI devices or busses, I don't know
> if the latest qemu versions have the ability to do this at a
> hardware-independent level like VMWare does (VM sends standard
> SCSI requests to qemu virtual SCSI adapter, qemu sends those
> same SCSI requests to real SCSI hardware via something like the
> Linux "SCSI generic" driver, optionally mapping at most the
> SCSI-level bus address).
>
> On 10/04/2019 19:42, Lars Bonnesen wrote:
> > But for sure I want passthru - for running virtualized SAN and such
> >
> > Any unofficial list?
> >
> > Regards, Lars.
> >
> > On Wed, Apr 10, 2019, 18:58 Friedrich Oslage <
> address@hidden>
> > wrote:
> >
> >> As long as it's VT-x capable and can run Linux, you're good to go.
> >>
> >> It only gets tricky once you start using VFIO (direct passthrough of
> >> host PCI devices to a VM, such as GPUs, NICs or NVMes for instance). You
> >> need VT-d support for that and both the CPU and mainboard have to
> >> support it. And not only do they have to support it, they have to
> >> support in a usable way with decent iommu group isolation and without
> >> weird bugs. There are no (official) compatibility lists for this, it's
> >> still mostly trial and error...
> >>
> >> Regards
> >> Friedrich
> >>
> >> On 4/10/19 2:26 PM, Lars Bonnesen wrote:
> >>> So I am coming from the VMware world (with comprehensive compatibillity
> >>> lists) but about to start a project with KVM/Qemu and I would like to
> >> setup
> >>> an inexpensive test setup for this purpose.
> >>>
> >>> I am thinking of buying one of SuperMicros IoT-servers like
> >>>
> >>
> https://www.supermicro.com/products/system/Mini-ITX/SYS-E300-9D-4CN8TP.cfm
> >>> Will this be a nice pick for Qemu? Or any VT-supportet system will work
> >>> fine?
> >>>
> >>> Regards, Lars.
>
>
> Enjoy
>
> Jakob
> --
> Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
> Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
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