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Old 06-11-2008, 11:03 PM
 
Default Centos 5.2 and Xen

If you only have 512mb of ram, there's almost no reason to virtualize. Windows needs a minimum of 128-512MB to run stable. I highly suggest that you get more RAM - its very cheap these days.

If you want to dedicate a box to virtualization, and won't be using more then 4GB of ram for your virtual machines - I highly recommend xenserver express. Its free, but has much better performance then vmware.

Looking at it more closely, it seems to be rhel5, or more likely centos5 under the hood, so you can probably use the host for other things too.

I wonder if it can be combined with other techologies - KVM, openVZ, etc to give more then 4GB of ram for virtualization? I tried installing vmware, but it wouldn't run under.a xen kernel.

RuSs
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: "Lanny Marcus" <lmmailinglists@gmail.com>

Date: Wed, 11 Jun 2008 17:22:12
To:"CentOS mailing list" <centos@centos.org>
Subject: Re: [CentOS] Centos 5.2 and Xen


On 6/11/08, Ned Slider <ned@unixmail.co.uk> wrote:
<snip>
> I've run VMware Server (free, as in cost, not as in open source) on
> CentOS to host WinXP VMs since it was in beta and have no complaints.
> There is an RPM package available on VMware's site:
>
> $ rpm -q VMware-server
> VMware-server-1.0.6-91891.i386
>
> It's only available in i386 package but installs fine on x86_64 and
> supports 64-bit VMs provided the underlying hardware supports it. I
> believe VMs are limited to a max of 2 processors each.
>
> I've used VMware Server on systems varying from old AthlonXP, 512MB RAM
> through to Intel Quad Core Q6600 with 4GB RAM. Note VMware will run on
> older processors without hardware virtualization. In my experience
> there's little noticeable difference between software and hardware
> virtualization (on VMware), and each run at about the perceived speed
> you would expect if it was on native hardware (I've not conducted any
> benchmark tests). The main consideration is that you have enough RAM to
> support the host OS (CentOS) and any VM(s) running on it.
>
> I've not used Xen so can't offer a comparison.

Ned: I was very interested to read that you've run VMWare Server on
systems with only 512 MB of RAM. I haven't tried it, because the box
I can use only has 512 MB of RAM.

My impression is that Xen is much more demanding about HW. Lanny
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Old 06-12-2008, 12:38 AM
Luke S Crawford
 
Default Centos 5.2 and Xen

russ@vshift.com writes:
> If you only have 512mb of ram, there's almost no reason to virtualize. Windows needs a minimum of 128-512MB to run stable. I highly suggest that you get more RAM - its very cheap these days.

seconded. my standard server has 8G unbuffered ecc. Newegg sells
2x2Gb packs of unbuffered ECC kingston brand ddr2 for under $100.

http://www.newegg.com/Product/Product.aspx?Item=N82E16820134312

No reason, really, to not fill your motherboard with ram.

> If you want to dedicate a box to virtualization, and won't be using more then 4GB of ram for your virtual machines - I highly recommend xenserver express. Its free, but has much better performance then vmware.

the free (closed) xensource product is good... I also wanted to point out
the new gpl windows pv drivers:

http://wiki.xensource.com/xenwiki/XenWindowsGplPv/

you could use them with the standard open-source Xen, or even with the
Xen support distributed with CentOS 5, and avoid the ram limits all together.
(well, there is a limit to the open-source xen, but it's ridiculous; most
of us won't hit it for several years, at least.)

still kinda beta, but something to watch.


> I wonder if it can be combined with other technologies - KVM, openVZ, etc to give more then 4GB of ram for virtualization? I tried installing vmware, but it wouldn't run under.a xen kernel.

running vmware under a xenU guest wouldn't lift any ram limit imposed by the
xen kernel or dom0.

the 4Gb limit is added to the free (closed source) citrix xen product
so that people have a reason to pay for the full version... really,
if you need more than 4G, pay for full xensource, or use the open-source
Xen/open source pv drivers.


I do know some people that run linux vserver guests under a Linux Xen DomU-
that seemed to work ok.

and just for fun, I've run a Xen kernel/Dom0 under a Xen HVM DomU.
Performance wasn't great; I don't think I'd do it in production, but
it worked, and was a neat experiment.
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Old 06-12-2008, 01:46 AM
Ruslan Sivak
 
Default Centos 5.2 and Xen

Luke S Crawford wrote:


I wonder if it can be combined with other technologies - KVM, openVZ, etc to give more then 4GB of ram for virtualization? I tried installing vmware, but it wouldn't run under.a xen kernel.



running vmware under a xenU guest wouldn't lift any ram limit imposed by the
xen kernel or dom0.


the 4Gb limit is added to the free (closed source) citrix xen product
so that people have a reason to pay for the full version... really,
if you need more than 4G, pay for full xensource, or use the open-source
Xen/open source pv drivers.


The 4GB limit is artificial, and only applies to the vm's started using
their closed source XenSource. The host OS is most likely CentOS 5, and
sees the whole 8GB (although it's not x64, so I'm guessing they use PAE
or something.)


I only need 8GB of ram support, and no other features that are offered
in XenStandard, so it seems kind of a waste to pay $1k per server for
that.

If another virtualization technology was installed on that OS, you can
get the use of the other 4GB, and if not, I can always run my apps on
Dom0, although I'd prefer to not install too much stuff on Dom0.


Russ
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Old 06-12-2008, 03:25 AM
Ruslan Sivak
 
Default Centos 5.2 and Xen

Luke S Crawford wrote:

russ@vshift.com writes:

If you only have 512mb of ram, there's almost no reason to virtualize. Windows needs a minimum of 128-512MB to run stable. I highly suggest that you get more RAM - its very cheap these days.



seconded. my standard server has 8G unbuffered ecc. Newegg sells
2x2Gb packs of unbuffered ECC kingston brand ddr2 for under $100.


http://www.newegg.com/Product/Product.aspx?Item=N82E16820134312

No reason, really, to not fill your motherboard with ram.


If you want to dedicate a box to virtualization, and won't be using more then 4GB of ram for your virtual machines - I highly recommend xenserver express. Its free, but has much better performance then vmware.



the free (closed) xensource product is good... I also wanted to point out
the new gpl windows pv drivers:


http://wiki.xensource.com/xenwiki/XenWindowsGplPv/

you could use them with the standard open-source Xen, or even with the
Xen support distributed with CentOS 5, and avoid the ram limits all together.

(well, there is a limit to the open-source xen, but it's ridiculous; most
of us won't hit it for several years, at least.)

still kinda beta, but something to watch.






Yea, I've been playing around with this. The performance seems on par
with the XenSource drivers, but like you said, it's pretty beta. James
has been great in fixing the bugs, but it's just not ready for
production use right now. Without using the GPLPV drivers, Xen is not
ready for production use, the IO throughput sucks, and there is no
graceful shutdown.

If XenServer Express would only allow for 8GB, it would be perfect. The
administrative interface is really polished and fully featured (except
things like migrations, which understandably come with the enterprise
version).

Once the GPLPV drivers mature a little bin and someone makes some decent
admin tools for Xen, Xen will be ready for the enterprise. I bet a
company can make good money just developing and selling the admin tools
for Xen.


Russ
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Old 06-12-2008, 06:24 AM
"Victor Padro"
 
Default Centos 5.2 and Xen

On Wed, Jun 11, 2008 at 10:25 PM, Ruslan Sivak <russ@vshift.com> wrote:

Luke S Crawford wrote:


russ@vshift.com writes:

*


If you only have 512mb of ram, there's almost no reason to virtualize. Windows needs a minimum of 128-512MB to run stable. *I highly suggest that you get more RAM - its very cheap these days. * * *




seconded. *my standard server has 8G unbuffered ecc. *Newegg sells 2x2Gb packs of unbuffered ECC kingston brand ddr2 for under $100.



http://www.newegg.com/Product/Product.aspx?Item=N82E16820134312



No reason, really, to not fill your motherboard with ram. *

*


If you want to dedicate a box to virtualization, and won't be using more then 4GB of ram for your virtual machines - I highly recommend xenserver express. *Its free, but has much better performance then vmware. * * *





the free (closed) xensource product is good... I also wanted to point out the new gpl windows pv drivers:



http://wiki.xensource.com/xenwiki/XenWindowsGplPv/



you could use them with the standard open-source Xen, or even with the Xen support distributed with CentOS 5, and avoid the ram limits all together.

(well, there is a limit to the open-source xen, but it's ridiculous; *most

of us won't hit it for several years, at least.) *

still kinda beta, but something to watch. *



*




Yea, I've been playing around with this. *The performance seems on par with the XenSource drivers, but like you said, it's pretty beta. *James has been great in fixing the bugs, but it's just not ready for production use right now. *Without using the GPLPV drivers, Xen is not ready for production use, the IO throughput sucks, and there is no graceful shutdown.


If XenServer Express would only allow for 8GB, it would be perfect. *The administrative interface is really polished and fully featured (except things like migrations, which understandably come with the enterprise version).


Once the GPLPV drivers mature a little bin and someone makes some decent admin tools for Xen, Xen will be ready for the enterprise. *I bet a company can make good money just developing and selling the admin tools for Xen.




Russ

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Perhaps you could be interested in this project:

I discovered three major issues in the usage scenarios of OpenVZ in the enterprise market:
Installation takes time and needs Linux knowledge
The missing GUI managementAnd the inability to run unmodified guests like Windows on an OpenVZ hostI
also had other wishes like integrated backup and restore,
live-migration, central configuration management and integrated virtual
appliances download. So I presented this last year to our development
team – a few months later, we proudly presents the first release of our
Proxmox Virtual Environment.

Now we have the virtualization platform for the enterprise, licensed under GNU GPLv2.

Proxmox VE is the only virtualization platform which can do all of the following on one physical host:

Container Virtualization (OpenVZ)Full virtualization (KVM)Para-virtualization (KVM) We encourage everybody to test Proxmox VE and give feedback, for download and documentation please visit the Proxmox VE Wiki.


Feel free to get in contact with me directly - martin@proxmox.com.



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Old 06-13-2008, 02:16 AM
Ruslan Sivak
 
Default Centos 5.2 and Xen

Victor Padro wrote:


*Perhaps you could be interested in this project:
*
I discovered three major issues in the usage scenarios of OpenVZ in
the enterprise market:


1. Installation takes time and needs Linux knowledge
2. The missing GUI management
3. And the inability to run unmodified guests like Windows on an
OpenVZ host

I also had other wishes like integrated backup and restore,
live-migration, central configuration management and integrated
virtual appliances download. So I presented this last year to our
development team – a few months later, we proudly presents the first
release of our *Proxmox Virtual Environment <http://pve.proxmox.com/>.*


Now we have the virtualization platform for the enterprise, licensed
under GNU GPLv2.


Proxmox VE is the *only *virtualization platform which can do all of
the following on one physical host:


* Container Virtualization (OpenVZ)
* Full virtualization (KVM)
* Para-virtualization (KVM)

We encourage everybody to test Proxmox VE and give feedback, for
download and documentation please visit the *Proxmox VE Wiki </>.*


Feel free to get in contact with me directly - martin@proxmox.com
<mailto:martin@proxmox.com>.


I tried installing this today, but it just goes to a blank screen after
loading the installer.


Russ

------------------------------------------------------------------------

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Old 06-13-2008, 08:24 AM
Peter Hinse
 
Default Centos 5.2 and Xen

Victor Padro wrote:

Proxmox VE is the *only *virtualization platform which can do all of the
following on one physical host:


* Container Virtualization (OpenVZ)
* Full virtualization (KVM)
* Para-virtualization (KVM)

We encourage everybody to test Proxmox VE and give feedback, for
download and documentation please visit the *Proxmox VE Wiki </>.*


Feel free to get in contact with me directly - martin@proxmox.com
<mailto:martin@proxmox.com>.


Sounds interesting, I just don't like the debian as underlying os for
the server ;-) However, since it's licensed under the GPL, I will try to
get it work with a redhat based linux.


Regards,

Peter

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Old 06-15-2008, 08:05 PM
"Robert - elists"
 
Default Centos 5.2 and Xen

I have an 8 gig dram server I am playing with Xen on in centos 5.1 on right
now.

Are you telling us that Xen on centos 5.1 only uses 4 Gig Dram?

Or will it allow all 8 Gig to be used if setup correctly between main dom
and virt doms

- rh


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Old 06-15-2008, 08:08 PM
"Tim Verhoeven"
 
Default Centos 5.2 and Xen

On Sun, Jun 15, 2008 at 10:05 PM, Robert - elists <lists07@abbacomm.net> wrote:
> I have an 8 gig dram server I am playing with Xen on in centos 5.1 on right
> now.
>
> Are you telling us that Xen on centos 5.1 only uses 4 Gig Dram?
>
> Or will it allow all 8 Gig to be used if setup correctly between main dom
> and virt doms

As far as my experience goes you can use the 8GB completely for all
the domU's. I think you are still limited to 4GB per domU.

Regards,
Tim

--
Tim Verhoeven - tim.verhoeven.be@gmail.com - 0479 / 88 11 83

Hoping the problem magically goes away by ignoring it is the
"microsoft approach to programming" and should never be allowed.
(Linus Torvalds)
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Old 06-15-2008, 09:41 PM
Ruslan Sivak
 
Default Centos 5.2 and Xen

Robert - elists wrote:

I have an 8 gig dram server I am playing with Xen on in centos 5.1 on right
now.

Are you telling us that Xen on centos 5.1 only uses 4 Gig Dram?

Or will it allow all 8 Gig to be used if setup correctly between main dom
and virt doms

- rh





I think if you're on an x64 bit platform you can use up to 8GB of ram
for dom0 (well you need to leave enough for dom0, mine takes up about
600mb after a clean install, and if you allocate too much to domU, the
server goes down - hard).


What I was talking about is XenServer - the commercial product based on
Xen now owned by citrix. They have a bare metal installer that installs
a version of CentOS 5 and their version of Xen in about 10 minutes, and
has a very nice windows based administrative console. Their free
version XenServer Express only allows DomU to use up to 4GB of RAM
collectivelly, and I believe only 4 VMs total. They also have fairly
nice paravirtualized drivers for windows (although James' GPLPV drivers
are catching up to them).


I think I will run XenServer at home where I have a box with only 4GB of
RAM, but for work, I'm probably going to go with CentOS 5.2 and Xen 3.2,
since XenServer is too limiting, and I don't think it's worth shelling
out $1k per box to get use of the other 3.5GB of RAM.


Russ
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