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Re: [Xen-users] Home Xen hypervisor for master's project

Hi Joseph, guys,

I must say that ECC is kinda market bull. I did used ECC enabled server and regular servers built from consumer parts. I've noticed no difference whatsoever.

Now, like Marek said, after you finish your thesis you might consider using it as a livingroom server. This will (maybe) involve running your workstation off it, as long with a Windows mediacenter with gaming capabilities. Also, you might consider creating a fileserver, a printserver, an voip/asterisk server etc. You will need as many cores as you can afford. With the latest AMD six cores you might be on the safe side. I've played around a bit with Windows as guest and for having a smooth movie or audio play, you need to dedicate a couple of cores to that VPS. If you share it with other VPSs, you get chunky sound or video. Giving away just one core is making the Windows VPS tooo slooooow to actually enjoy it. And yes, definitely go for IOMMU! The 890FX chipset is what I have, and it works great. I've tried some other chipset and this really makes the difference (the other just hanged, poor support for IRQ mappings, etc).

Also, if you will run it from home, you should consider the power consumption and also the noise. If you don't want to house it in a soundproof closet, you might want to go for ATX and buy a regular or a silent case. If you are just experimenting (ie no financial profit from it) you might consider keeping the electricity bill as low as possible. There are a few green solutions for both CPUs and hard drives. You won't need the black editions of neither one, as your load will be low most of the times, just spiking when doing intensive stuff like compiling the kernel. Not to mention the video card: try choosing now a green model (eg ATI 5450). Later on, after you finish your thesis, you might consider buying a more expensive and much better video card for gaming and pass that entirely to the Windows VPS.

I do have setup at home a similar Xen system and I must say I'm very happy with it. I only have one physical computer and a bunch of virtual ones. Benefits: initial costs, power consumption, noise, storage space. Cons: if the hardware goes off, you have no computer at all. :)

All the best wishes from Romania!

On 20.02.2011 04:58, Marek Kaszycki wrote:
Dnia 20-02-2011 o 02:44:32 Joseph Commisso <commissoje@xxxxxxxxx> napisał(a):


Can you help me in identifying some of the tradeoffs of going with the
Xeon/Opteron vs the Phenom II/Core i5 or i7?
This is where the difference between Intel and AMD is the biggest. Intel seems to be disabling CPU features at random and this will lead to problems with virtualization. Assuming you are interested in going with at least a quad core. Three cores may also be enough, but two would likely be too few if you want to run several VMs at once. This immediately limits your options to only some CPUs. I assume you won't be getting a Sandy Bridge i5 due to the SATA 2 controller issue in the chipset, so the only i5 is Lynnfield (750 and 760), but neither has support for VT-d. All Lynnfield Core i7 CPUs support VT-d apart from 875K (just so you know, I don't think you were interested in that one, anyway). Support for VT-d with 900 series depends on the motherboard and its BIOS.

Conversely, AMD enables everything on its entire CPU range. If it's based on K10.5, it will have support for AMD-V, memory ECC, and with the right motherboard (currently limited to 890FX-based), IOMMU. Your choice, but for virtualization, especially on a budget, nothing beats AMD.

I know that server grade CPUs are constructed totally different than
general desktop CPUs, but I do not know why or how that would effect
my processing environment and my experience on this system.
Not totally different. If anything, some features may have been fused off, but otherwise the dies are exactly the same. Since Intel is using LGA across the board, they have the same mounting as well (AMD uses PGA sockets, while all current Opterons use LGA). One feature missing from consumer version of Intel CPUs is lack of support for ECC on any of the buses (I'm not sure about cache ECC). This is important, because if you want to run a server, you'll want to have ECC protection on pretty much everything, so if you want to go with Intel, get a Xeon (even i7-900 series don't support ECC memory or QPI). AMD, on the other hand, does support ECC on both HyperTransport (by design) and on the memory controller with all current consumer CPUs. Fundamentally, however, there are no differences between the enterprise and the consumer versions of a given CPU. If any given software demands a 'server-grade CPU', rather than server-specific features, it's usually bogus, since, e.g., an Athlon with ECC memory is server grade, while an Opteron with no-ECC memory is not, regardless of the CPU brand.

I certainly would like to make the purchase right away, but it seems
that I have many questions as to what will work out best and the
answers are not easy for me to find. At least they aren't easy for me
to find!
If you want to wait, Intel will have fixed Sandy Bridge chipsets by March and revised motherboards may hit the market in volume by mid-March. Going for that will give you a wider choice of CPUs with VT-d support (although still not as wide as you'd probably like and still no support for ECC).

Now, all the above assumes that you will want to make use of VT-d/AMD-Vi. Once you finish your thesis, I doubt you'll continue running the cloud services (for which VT-d is maybe an afterthought), but you will want to make the machine relevant for home use. If you prefer running a Linux desktop, but you'd still like to play the latest games in a Windows VM (where IOMMU shines), then there's no choice, but to go for something that supports IOMMU. Note that using a machine at home usually implies that you won't be needing ECC, so if you're fine with no ECC, then feel free to disregard the caveat about Intel Core CPUs.


Thank you for anything you may be able to help with,

On Sat, Feb 19, 2011 at 8:15 PM, Ryan Holt <ryan@xxxxxxxxxxxx> wrote:
I recently built a home Xen server to both play with and run a few servers at my house. I decided I'd spend a little more money and get server grade gear and have been very happy with what I have so far:


You'll need a few disks and a case. I used software RAID and used the 6 SATA connectors on the board along with an old Coolermaster case. I purchased 3x 5.25 to 5x3.5" hdd adapter to make things easier. Next I'll buy one of these cases to replace the Coolermaster that it's currently running in:


-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Todd Deshane
Sent: Saturday, February 19, 2011 8:11 PM
To: Joseph Commisso
Cc: Xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Home Xen hypervisor for master's project

On Sun, Feb 20, 2011 at 1:02 AM, Joseph Commisso <commissoje@xxxxxxxxx> wrote:
On Sat, Feb 19, 2011 at 7:21 PM, Todd Deshane <todd.deshane@xxxxxxx> wrote:
On Sat, Feb 19, 2011 at 8:02 PM, Joseph Commisso <commissoje@xxxxxxxxx> wrote:
Hi all,

Could somebody please help me with a few hardware questions?

I am building a home Xen server to implement a Xen Cloud for my
master's project comparing SOA.
I will probably use Linux guest OSs, but I may want to use a Windows
guest for home PC use.

Can you go into more detail about what features you plan to implement?

Well, I really do not know too much about Cloud computing, grids
(Globus), or parallel programming, all of which I would like to touch
upon or possibly go into more depth.

You might find these useful for background (you or your school will need an ACM account):

I was thinking of implementing a grid on the cloud, but then I saw
documentation referring to a cloud on a grid, so when I get there, I
will work that one out.
My instructor said to compare what I do against SOA, which will give
me something to work on there as well.

I am fairly proficient with Linux administration with some abilities
on other areas, like networking, hardware and some minor software
So, I do not know what I will need to implement at this point. I hope
to learn as I go and see if I can come up with something useful.
I want to build this virtual server at home, since the machines that I
have access to at school are slow and also because school is 50 miles
away and I have no other classes to attend, so working at home on this
seems like the way to do it.

Also, what type of interfaces do you expect to provide to users? How
will they connect? etc.

What I know how to do is use xdmcp for remote sessions.
If I do set up a grid or cluster, then there may be some interface
which that uses.
Again, I hope to be able to find out when I get there.
I plan on choosing a motherboard/CPU and then building the rest of the
machine around those.
I have a coworker who suggested the AMD line and said that due to the
way the CPU connects to the bus and the rest of the motherboard, that
three cores is optimal.
I did not get a chance to talk to him about a hypervisor machine and
whether that also applied to the three cores.

I have been trying to make a decision on the CPU and motherboard to
purchase and really could use some help.

I have read the wiki post at:

1) For my purposes, is IOMMU important?
If so, then also, for my purposes, it looks like the ASUS Crosshair
IV Formula may be a good choice.

** I would appreciate any input, as to the Crosshair or other, like the M4A89TD.

Now for the CPU and I have really not been able to determine how
many cores is optimal for this server.
I have a knowledgeable coworker who says that three cores is optimal
and I have not been able to find information to support that or
dispute it.

2) The Phenom II series seems to be attractive, so I have been
concentrating on those, but can someone also help me with the X3,
X4, or X6 decision?


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