[Info-vax] VSI Rolling Roadmap, June 2016

[Paul Sture]

On 2016-06-13, clairgrant71 at gmail.com <clairgrant71 at gmail.com> wrote:
> On Saturday, June 11, 2016 at 4:57:34 AM UTC-4, Paul Sture wrote:
>
>> 
>> Has anyone come across a comparison of kvm and xen?  I've looked several
>> times over the last 5 years or so but came up with a blank each time.
>> 
>
> I can't give you a side-by-side comparison but I have worked with both
> during the last year and they are very different. Kvm is what I would
> call a classic hypervisor, a SW product that runs on top of an OS.
> Some might call it middleware or maybe a sophisticated application. It
> creates and manages virtual machines and uses the features of the
> underlying OS to facilitate most operations. Xen is close to being a
> pure, bare-metal hypervisor but not quite. Xen itself consists of
> memory management, scheduler, and CPU management but it has no device
> drivers. Domain 0, a special virtual machine, runs a complete OS, in
> my case CentOS but it can be others. Xen creates an in-memory "path"
> between each regular vm and Dom0's I/O system for device access.
> That's the big architectural difference between kvm and xen.

Thanks very much Clair. It's a lot clearer now.

> Most hypervisors default to booting BIOS in the virtual machines. VMS
> wants UEFI. KVM (and VirtualBox) have a nice option for that and it is
> also easy to toss in your own boot loader, exactly what we want.

A quick search got me here for VMware (instructions for VirtualBox and
Hyper-V also included): 

<http://www.serverwatch.com/server-tutorials/enabling-uefi-on-virtual-machines.html>

Not as "user friendly" but UEFI can be enabled in VMware Player and
Workstation by editing the relevant .vmx file and adding the line:

firmware = "efi"

A quick peek at my VMware instance of OS X reveals that the same tweak
applies to VMware Fusion.

> Xen isn't as easy since you have to rebuild xen to include UEFI, at
> least in the version I'm using.
>
> One interesting thing about xen is that there are multiple schedulers
> available, usually for specific types of workloads.

That sounds rather useful.

-- 
There are two hard things in computer science, and they are cache invalidation,
naming, and off-by-one errors.