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Re: Multi-Boot Servers and Virtual Servers with GNU/Linux

  • Subject: Re: Multi-Boot Servers and Virtual Servers with GNU/Linux
  • From: Rex Ballard <rex.ballard@xxxxxxxxx>
  • Date: Wed, 26 Aug 2009 15:56:18 -0700 (PDT)
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On Aug 26, 5:55 pm, Roy Schestowitz <newsgro...@xxxxxxxxxxxxxxx>

> Windows drivers for KVM
> ,----[ Quote ]
> | Red Hat has released paravirtualised network
> | and storage drivers for running
> | Windows guest systems under the KVM
> | (Kernel-based Virtual Machines)
> | virtualisation solution for Linux.  
> `----

Red Hat is a bit late to the party.  I've been using RHELD 5 with
VMWare Workstation to run Windows VM for a while now.

Strange as it seems, Linux as the host actually IMPROVES the
performance of Windows over "Native" mode.  To begin with, even plain
old 32 bit Linux can fully utilize up to 4 gig of RAM.  32 bit Linux
with PAE can utilize up to 32 gig of RAM if you have it.  Linux uses
the RAM not allocated to applications as disk buffers, allowing it to
read cylinders at a time, then feed it to the application as
requested.  Windows reads 4 KB clusters at a time, which is now
substantially less  than a cylinder.  Since Linux sucked down as much
as it could in a single rotation, the Windows system doesn't have to
wait as it reads or writes to the drive.

In "Native" windows, on a 7200 RPM drive, I get no more than about 400
kilobytes per second file transfers, because of the rotational
latentcy.  When I run Windows VM on Linux, the transfer speed often
exceeds 1 megabyte per second, as much as 3 times faster, even when
doing transfers between USB drives and internal drives.

This is with RHELD Linux running on a 4 Gig Y730 with 500 Gb 7200 RPM
hard drive, and a Windows VM running Windows XP on 2 Gig VM memory,
and 30 GB virtual hard drive.

Microsoft is even beginning to acknowledge that many users may want to
use Linux to "enhance" the Windows OS sold with their PCs.  Windows 7
may actually even be more effective in supporting that kind of access.

Vista had support for safely shrinking the Windows partition, and
Windows 7 has a hypervisor friendly kernel.

> http://www.h-online.com/open/Windows-drivers-for-KVM--/news/114085

> Linux as host.

> Recent:

> Red Hat's standalone hypervisor goes beta

> ,----[ Quote ]
> | Commercial Linux distributor Red Hat threw its, er, red hat into the
> | virtualization ring back in February when it announced it was creating a
> | standalone Enterprise Virtualization hypervisor based on KVM to
> | compete with
> | the likes of VMware, Microsoft, and Citrix Systems.
> | Today, that standalone
> | hypervisor and the tools to manage it for
> | servers and desktops moved into
> | beta.
> `----

> http://www.theregister.co.uk/2009/06/16/redhat_rhev_beta/

The critical thing is the tools to manage it.  One of the reasons that
VMWare has been so successful is that they have such robust tools to
make it very easy to create VMs from physical images, to run multiple
images, and to fully back-up and restore images using snapshots.

I've set up Xen a few times, and found it a bit frustrating.

What would be very nice would be having the ability to set up a system
as "dual boot", then having the hypervisor "boot" the secondary image.

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