Scott,

Thanks for your input. The article was a good read.

Reference: Athlon 64 x2 system with 8GB of memory.

I've got a few issues that have me vacillating: - Ease of use, i.e., I'm being lazy and customizations can be time consuming. :) - Xen being built into the CentOS build is a large positive factor. - Xen's Express version limitations: 4GB RAM and 4 VM. Bad thing. - Windows 2003 Server is one Guest OS. There will be several of these, i.e., an M$ infrastructure. - *nix variants: Solaris and Fedora. - The version of VMWare is the freebie. The unmodified OS support is a big plus.

I guess I could run two Linux on Linux VM's and have two Xen hosts running to get around their limitations?

This does seem a bit obsessive though! ;)

----- "Robert Holtz" Robert.Holtz@edwardjones.com wrote:

The two main ones that I know of are Xen and VMWare. VMWare seems to be the most capable inre: number and size of vm's allowed. When looking at Xen it appears that since Citrix acquired them the free version is cripple-ware and is very restrictive.

Xen virtualization is included as part of CentOS 5. Xensource's XenServer Exoress Edition, so far as I can tell, hasn't changed at all since Citrix took them over - dual-socket with upto 4GB of RAM, and four virtual machines. What does XenSource's product have to do with CentOS.

Regarding VMware, are you talking about the free VMware Server or the very expensive VMware ESX/Infrastructure? If the former, there is a lot more overhead with VMware Server when compared to Xen but VMware Server will allow you to run unmodified OSes... whereas Xen requires VT hardware support in the CPU to create fully-virtualized aka unmodified OSes.

If you are wanting to run Linux on Linux, I'd recommend you look into OpenVZ and/or Linux-VServer.

Oh, and while I'm here, I'll plug my recent interview with the Linux-VServer project leader:

Interview with Linux-VServer Project Leader Herbert Pötzl http://www.montanalinux.org/linux-vserver-interview.html

TYL, -- Scott Dowdle 704 Church Street Belgrade, MT 59714 (406)388-0827 [home] (406)994-3931 [work]

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Scott,

Thank you again for the excellent feed back.

I still have much hand-wringing and reading to do before falling either direction. The hardest past is reading between the lines of all of the information out there, i.e., marketing fluff. It appears that VMWare likes to throw the Hypervisor phrase around too but it's a thing on a thing where my understanding of Xen is that it's tightly coupled with the OS. More research!

I'm certain I'll have more questions as I go along.

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-----Original Message-----

From: centos-virt-bounces@centos.org [mailto:centos-virt-bounces@centos.org] On Behalf Of Scott Dowdle Sent: Friday, November 09, 2007 3:04 PM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] New to the list ... Looking foranyrecommendations inre: VMWare Vs. Xen

Robert,

----- "Robert Holtz" Robert.Holtz@edwardjones.com wrote:

I've got a few issues that have me vacillating:

• Ease of use, i.e., I'm being lazy and customizations can be time

consuming. :)

If you made that statement regarding installing OpenVZ or Linux-VServer, they are really easy to install. OpenVZ is a bit more friendly and offers a yum repo for both CentOS 4 and 5 and you can get up and running in about 10 minutes if you follow the OpenVZ quick install guide. If you search www.montanalinux.org for openvz you'll find two screencasts that might be of interest.

Creating guests, once you have an OS Template to install from (download or create your own), takes about 10 seconds.

• Xen being built into the CentOS build is a large positive factor.

Yes.

• Xen's Express version limitations: 4GB RAM and 4 VM. Bad thing.

Yes, but you can aways buy their non-free products. They are reasonably priced. One main difference is ease of use. XenSource (which was based on CentOS last time I checked) has a really nice GUI management interface and has some additional capabilities not found in VirtManager... I believe. I'm a little outdated on them both. XenSource's management app used to be a multi-platform (Java-based) but I think the most recent release replaced the GUI app with a Win32 app. :( I don't necessarily recommend XenSource over the Xen in RHEL/CentOS though. Just depends on what you are looking for. XenServer is dead easy to install and the management interface (I've used the previous version) really is a turnkey type thing. However if you are familiar with RHEL/CentOS already, "Red Hat Virtualization" and the VirtManager are pretty good.

RHEL 5 Update 1 came out this week... and it'll be a little while before CentOS 5.1 comes out... but there are enough changes in Xen that you'll probably want to wait for that.

• Windows 2003 Server is one Guest OS. There will be several of

these, i.e., an M$ infrastructure.

That rules out OpenVZ and Linux-VServer as they can't run other OSes.

• *nix variants: Solaris and Fedora.

OpenVZ only supports Linux but there are a number of OS Templates (aka install media) for various distros.

• The version of VMWare is the freebie. The unmodified OS support is

a big plus.

Yes, but as stated the free VMware Server is not hypervisor based and has a LOT of overhead compared to Xen and VMware ESX. If you have sticker shock over XenSource's products, you'll go into a comma over VMware's.

I guess I could run two Linux on Linux VM's and have two Xen hosts running to get around their limitations?

If your talking about needing two Xen hosts so you can run two copies of the free XenServer Express, I'm guessing a second physical machine costs more than the XenServer ($495)... but more power to you.

TYL, -- Scott Dowdle 704 Church Street Belgrade, MT 59714 (406)388-0827 [home] (406)994-3931 [work]

_______________________________________________ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt

Hmm ... You make an good point.

So it sounds to me that ease of use and performance can both be achieved with VMWare on *nix.

Over the past 20+ years I've had far too many driver nightmares on multiple operating systems so this is something that can easy drive me away. I'm just going for the path of least resistance.

When you tested the two against each other what were your metrics ... just curious. Since I'm, more or less, looking to build a server farm (4 MS) I'm not concerned about video but hard drive performance would be of interest. The other *nix VM's mentioned: Solaris & Fedora, are just for reference so performance on these is a non-issue.

This drifts a bit off topic but what are your thoughts on running VM's on their own hard drives, i.e., having all of the VM files stored on a RAID5 volume or each on its' own HDD? I'm looking at RAID5 for the primary storage volume (nVidia motherboard based).

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-----Original Message-----

From: centos-virt-bounces@centos.org [mailto:centos-virt-bounces@centos.org] On Behalf Of Fabian Arrotin Sent: Friday, November 09, 2007 3:23 PM To: Discussion about the virtualization on CentOS Subject: RE: [CentOS-virt] New to the list ... Looking foranyrecommendations inre: VMWare Vs. Xen

Then forget about Xen (just my opinion) , i mean Xen without proprietary drivers for the emulated nics, scsi controllers etc ...

I've seen during my tests that it's faster to run a Windows (with the freely available/included vmware guest drivers) box inside of Vmware server than the same Windows (without any optimized drivers, because not availble) in Xen ...

I know that such 'accelerated' drivers for Xen are available from Xensource and were announced also by Novell (for a annual price of 300 $ / guest iirc ! , to be verified though).

Red Hat announced the same thing (no prices yet) for the xen optimized drivers for unmodified OSes for 5.1 ...