[ale] almost OT: Hardware for virtualization

Kaerka Phillips kbphillips80 at gmail.com
Fri Aug 19 12:21:59 EDT 2011


I build Dell PE 2950's up to R910's as KVM servers in my day job, so I also
wanted to setup something similar at home.  I used an Asus M3A78-EM board,
8gb of ddr2 1066 ram, an AMD Phenom II X4 940, and several sata hard
drives.  I went with RHEL 6.1 for my hypervisor OS, but I'd recommend Fedora
or CentOS instead in order to be able to install packages without requiring
an entitlement.

I'd also recommend separating out your VM locations to a second disk unless
you have a caching raid card and/or some sort of raid configured.  The
primary reason for that is to reduce i/o contention between your OS location
and the virtual machines.  Using a 32gb SSD for the OS and a 1tb sata 3
drive is a good compromise.

Also, I highly regret having used a mobo that only supports 8gb ram - 4 to
8gb is fine to start with, but once you reach your limits there, you'll find
that you want to expand, but cannot.  I'd recommend getting a mobo that
supports 16gb or more, and only installing an initial 4 to 8 gb in the
largest dimms that you can afford, leaving it open for easy expandability
later on.

For KVM - I really don't like it's integration into dnsmasq, mainly in that
if you want to use dnsmasq for other things as well, virt-manager will
occasionally disagree with nice python errors when working with the network
configurations of the hypervisor.  Same thing for some uses of avahi (no
idea why on that one).

Kaerka

On Thu, Aug 18, 2011 at 4:30 AM, Jim Lynch <ale_nospam at fayettedigital.com>wrote:

> On 08/17/2011 01:25 PM, JD wrote:
> > On 08/17/2011 12:09 PM, Boris Borisov wrote:
> >> I never done any installation of virtual servers and I want to start
> experimenting with the technology. Whats is the minimum CPU+MB that I can
> buy in Microcenter ( I work nearby ) for my needs. Bear in mind is going to
> be only for tests learning purpose not for production :)
> >>
> >> Thank you for all suggestions !
> > Key things are:
> >
> > * Lots of RAM - You need enough RAM for the host OS AND all the
> > clientOSes that will run at the same time. This may be 1GB if you are
> > cheap, but you'll be much happier with 6-16GB of RAM. I have 6GB and 8GB
> > machines with
> >
> > * Virtualization support built into the CPU.  Intel called it "VT-x".
> > Unfortunately about half the CPUs Intel makes do not support this still.
> > The only way to be certain is to look up a specific CPU model and
> > submodel number on the Intel web site.  AMD calls this something
> > different. For awhile, AMD shipped 90% of their CPUs with this built-in.
> > Something happened and they don't anymore. Check the AMD website.
> >
> > * CPUs with 2 or more Cores.  I get good results from fast C2D CPUs, but
> > the Core i5-2500K seems like the sweet spot on capabilities and price.
> > I'm extremely impressed with a 3 yr old Core i5-750 still.  AMD systems
> > with 4-6 cores probably work really well too.  More cores probably means
> > more power required.
> >
> > * You may want a CPU/motherboard with VT-d support. Look up what that
> > means, then get out your wallet.
> >
> > * Disk storage for each VM.  MS-Windows seems to need 20-30GB per VM.
> > Ultimate wants 45GB.  Linux distros use much less, from 50MB for
> > TinyCore to 10GB for a full Ubuntu desktop install with every bell and
> > whistle possible.  I usually give each server VM 4GB of storage and my
> > desktop VM just outgrew a 10GB allocation after 3 yrs of daily use.
> >
> > There are different types of virtualization - desktop and servers.
> > Server virtualization hardware can be extremely picky, so if that's
> > really what you want to learn, you would be well served by using the
> > VMware ESX Hardware Compatibility List http://www.vmware.com/go/hcl to
> > select hardware. I haven't looked in a while, but there was a time when
> > none of my systems could load ESXi due to the disk controller and
> > networking chipsets. It is THAT picky.
> >
> > For server-based virtualization, forget about the graphics card. It
> > doesn't matter beyond being able to show an 80x25 text console.
> >
> > Desktop virtualization is a little more forgiving, but don't expect to
> > play Windows games under a VM and be happy.  Don't expect hardware
> > passthru to work very well.  Graphics performance is fine for office
> > productivity apps, not so good for gaming or video editing.
> >
> > I'll be at the ALE-central meeting tomorrow night. Find me if you'd like
> > to discuss more.
> >
> > \
> OpenVZ doesn't dedicate any ram to a container.  I currently have 10
> containers running on a 2 Gb system quite happily.  Granted they aren't
> too busy but they are all up and most of them are serving web pages,
> some doing compiles some are running mysql, etc.  Htop shows it's only
> using 1 Gb.  If you need a lot of guests and want them to run as
> efficiently as possible. OpenVZ is your best choice.  I suspect lxc will
> give you similar results but I've not had any experience.  The
> documentation is a bit lacking as far as I can tell.
>
> Jim
>
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-- 

Kaerka Phillips
kbphillips80 at gmail.com
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