Hello:
I am new to Xen and have been having problems getting it to run properly on CentOS 5.2. One thing to note is that the base Xen installs fine it seems but when trying to create the virtual instance (domU) it says it cannot connect to the console. I have looked up the error but cannot find anything specific to try. I currently only have access to the server remotely via SSH, if this matters at all.
qemu: the number of cpus is 1
*** image /local/domain/0/backend/vbd/5/768 format raw driver 0x80e7940
*** image /local/domain/0/backend/vbd/5/5632 format raw driver 0x80e7940 Watching /local/domain/5/logdirty/next-active
Could not initialize SDL - exiting
I would really appreciate any assistance from anyone who knows Xen and CentOS.
Thanks
Jason
I am new to Xen and have been having problems getting it to run properly on CentOS 5.2. One thing to note is that the base Xen installs fine it seems but when trying to create the virtual instance (domU) it says it cannot connect to the console. I have looked up the error but cannot find anything specific to try. I currently only have access to the server remotely via SSH, if this matters at all.
I'm a Xen newbie myself, but it has worked fine for me so far using GUI tools and on a server that supports hardware virtualisation.
I suppose the first questions are:
Is xend running?
What tools are you using to create domU? Forgive me if I'm telling you something you already know, but on the command line your options are virsh and xm, virt-manager is GUI only AFAIK.
Are you working as root? You probably need to be.
Michael:
I was following the tutorial at http://www.howtoforge.com/centos_5.0_xen I was not aware that virt-manager is GUI only.
Xend does start and I can do everything listed in the tutorial until I get to the virt-manager part.
What command line do you use to create a virtual server with virtsh? I am running as root, so that shouldn't be the issue.
The hardware does support virtualization and that is switched on in the BIOS.
Thanks in advance,
Jason
-----Original Message----- From: centos-virt-bounces@centos.org [mailto:centos-virt-bounces@centos.org] On Behalf Of Michael Hall Sent: Saturday, November 15, 2008 6:56 P To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Need Help with Xen Please
I am new to Xen and have been having problems getting it to run properly
on
CentOS 5.2. One thing to note is that the base Xen installs fine it seems but when trying to create the virtual instance (domU) it says it cannot connect to the console. I have looked up the error but cannot find
anything
specific to try. I currently only have access to the server remotely via SSH, if this matters at all.
I'm a Xen newbie myself, but it has worked fine for me so far using GUI tools and on a server that supports hardware virtualisation.
I suppose the first questions are:
Is xend running?
What tools are you using to create domU? Forgive me if I'm telling you something you already know, but on the command line your options are virsh and xm, virt-manager is GUI only AFAIK.
Are you working as root? You probably need to be. _______________________________________________ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
On Sat, 2008-11-15 at 19:18 -0700, Jason Taylor wrote:
Michael:
I was following the tutorial at http://www.howtoforge.com/centos_5.0_xen I was not aware that virt-manager is GUI only.
Xend does start and I can do everything listed in the tutorial until I get to the virt-manager part.
What command line do you use to create a virtual server with virtsh? I am running as root, so that shouldn't be the issue.
The hardware does support virtualization and that is switched on in the BIOS.
You can use `virt-install` to install a guest. To my knowledge, you don't need any processor extensions to run Xen as it is a modified kernel for para-virtualisation.
For Xen management I just use `xm ${command}` and I've heard that you don't want to mix management with `xm` and `virsh`, so choose one and stick with it. `xm create ${domain}` will start the specified 'domain' with the config file of the same name in /etc/xen.
I hope that helps you out a bit :)
--Caitlyn
I was following the tutorial at http://www.howtoforge.com/centos_5.0_xen I was not aware that virt-manager is GUI only.
Xend does start and I can do everything listed in the tutorial until I get to the virt-manager part.
What command line do you use to create a virtual server with virtsh? I am running as root, so that shouldn't be the issue.
The hardware does support virtualization and that is switched on in the BIOS.
I just looked at 'man virt-manager', I think it's safe to say it is a GUI-only tool.
AFAIK, virsh is a general purpose RedHat virtualisation tool which can manage Xen but will also manage KVM when that goes mainstream.
xm on the other hand is a Xen-specific tool.
Both can be used to do much the same thing, but are reasonably involved, so your best bet at this stage is 'man virsh' and 'man xm'.
Sorry but as I said, I'm a Xen newbie myself and have only used the GUI tool to date.
Jason Taylor wrote on Sat, 15 Nov 2008 17:00:46 -0700:
One thing to note is that the base Xen installs fine it seems but when trying to create the virtual instance (domU) it says it cannot connect to the console.
Then try without making it connect to the console. (I may have misunderstood what you mean by "create", note, "create" means *starting* an existing VM. see below.)
I looked at the how-to, it uses virt-install. That works very well. What exactly did you install as a domU? What where your commands? And when do you get that error, when you run virt-install and it wants to attach to the console or once it's finished and you start the VM up?
One thing: you want to use the Xen 3.2 rpms provided by xen.org for serious production work on CentOS and not the one coming with CentOS. Suggest you read the archives of the list for all tips and caveats.
Kai
One thing: you want to use the Xen 3.2 rpms provided by xen.org for serious production work on CentOS and not the one coming with CentOS. Suggest you read the archives of the list for all tips and caveats.
When installing the xen.org RPMs, are existing VMs and config files etc dealt with gracefully?
Michael Hall wrote on Sun, 16 Nov 2008 21:34:25 +0930:
When installing the xen.org RPMs, are existing VMs and config files etc dealt with gracefully?
yes.
Kai
One thing: you want to use the Xen 3.2 rpms provided by xen.org for serious production work on CentOS and not the one coming with CentOS. Suggest you read the archives of the list for all tips and caveats.
I've been using the stock Xen (2.6.18) that comes with the latest CentOS 5.2 in production without major issue. At one time I had to restart xend occasionally to be able to properly reboot guest OSes from virt-manager, but even that has stabilized.
What specifically is better about 3.2 that you are recommended it over 2.6.18? My experience to date with CentOS is it tends to run the latest, proven stable version of each package, which would make me hesitant to run downloaded packages.
As far as virt-manager, use ssh -X or ssh -Y to connect to the DomU then start up virt-manager, this should reflect the GUI back to the originating workstation.
Brett
Brett Serkez wrote on Sun, 16 Nov 2008 07:16:45 -0500:
I've been using the stock Xen (2.6.18) that comes with the latest CentOS 5.2 in production without major issue. At one time I had to restart xend occasionally to be able to properly reboot guest OSes from virt-manager, but even that has stabilized.
What specifically is better about 3.2 that you are recommended it over 2.6.18?
AFAIK, you cannot run 32bit guests on 64bit hosts and the HVM support also lacks in the stock CentOS version (which is a 3.0.3/3.1 mix). As I'm not using both I can only reflect what others say. The latest version in 5.2 may also have some patches that Xen 3.2 has and thus works better. You are also getting the xenstore and it's functionality and better networking scripts (the virtual network interface structure changed significantly) with it. There were a lot of improvements from 3.0.3/3.1 to 3.2.
My experience to date with CentOS is it tends to run the
latest, proven stable version of each package, which would make me hesitant to run downloaded packages.
That specific package from xen.org runs really well, but you also have to add two or three patches.
Kai
Kai Schaetzl wrote:
What specifically is better about 3.2 that you are recommended it over 2.6.18?
AFAIK, you cannot run 32bit guests on 64bit hosts and the HVM support also lacks in the stock CentOS version (which is a 3.0.3/3.1 mix).
afaik, you would be wrong on both those counts. 5.2 still has 'preview only' 32bit on 64bit dom0 - but it does work and works fine for me on 2 diff machines.
As I'm not using both I can only reflect what others say. The latest version in 5.2 may also have some patches that Xen 3.2 has and thus works better. You are also getting the xenstore and it's functionality and better networking scripts (the virtual network interface structure changed significantly) with it. There were a lot of improvements from 3.0.3/3.1 to 3.2.
yes, that is clearly visible - much changes have gone into the 3.2 tree - but there is near zero maintenance work being done upstream, so once you are on the grindstone, you might need to stay on that in order to get the fix's you need. Also, the xen developers really seem to be loosing the plot with little or not real efforts being made to 'upstream xen foo'. Putting the distro buffer between myself and the technology makes me feel good too :D specially since I have a few xen machines in production now.
My experience to date with CentOS is it tends to run the
latest, proven stable version of each package, which would make me hesitant to run downloaded packages.
That specific package from xen.org runs really well, but you also have to add two or three patches.
on the flip side, I have much higher stability working with the distro packages, since i dont need to patch anything and the tooling works well too.
- KB
One thing: you want to use the Xen 3.2 rpms provided by xen.org for serious production work on CentOS and not the one coming with CentOS. Suggest you read the archives of the list for all tips and caveats.
On the downloads page at xen.org I can only see source tarballs for 3.3.
Am I looking in the wrong place?
Mick
Michael Hall wrote on Sun, 16 Nov 2008 21:59:35 +0930:
On the downloads page at xen.org I can only see source tarballs for 3.3.
There are no 3.3 rpms provided by xen.org. The fiels for 3.2 are in the archive: http://www.xen.org/download/dl_32rhel5.html
Again: before you use it, skim this group for the few patches you want to install and some other hints.
Kai
Michael Hall wrote:
One thing: you want to use the Xen 3.2 rpms provided by xen.org for serious production work on CentOS and not the one coming with CentOS. Suggest you read the archives of the list for all tips and caveats.
On the downloads page at xen.org I can only see source tarballs for 3.3.
Am I looking in the wrong place?
given that you are starting out with Xen now and getting into it, I would higly recommend you dont waste your time looking at the xensource / citrix package. Work with whats in the distro, its well tested as a unit, the tools just work and there is plenty of docs and help around to help when you need it.
Fix the problems you come up against, and if one of them needs an upgrade out of the distro packages - consider it at the time.
Hello Kai:
Thank you for your feedback. I apologize for not using the right terminology. As mentioned I followed the tutorial at http://www.howtoforge.com/centos_5.0_xen so that shows all the commands I used. When I tried to install a guest/domU I get the previous mentioned error. Virt-install doesnt seem to work as it seems to require a console which I do not have. All I have is root access to the server via SSH (not in same physical location as server)
Jason
-----Original Message----- From: centos-virt-bounces@centos.org [mailto:centos-virt-bounces@centos.org] On Behalf Of Kai Schaetzl Sent: Sunday, November 16, 2008 4:31 A To: centos-virt@centos.org Subject: Re: [CentOS-virt] Need Help with Xen Please
Jason Taylor wrote on Sat, 15 Nov 2008 17:00:46 -0700:
One thing to note is that the base Xen installs fine it seems but when trying to create the virtual instance (domU) it says it cannot connect to the console.
Then try without making it connect to the console. (I may have misunderstood
what you mean by "create", note, "create" means *starting* an existing VM. see below.)
I looked at the how-to, it uses virt-install. That works very well. What exactly did you install as a domU? What where your commands? And when do you
get that error, when you run virt-install and it wants to attach to the console or once it's finished and you start the VM up?
One thing: you want to use the Xen 3.2 rpms provided by xen.org for serious production work on CentOS and not the one coming with CentOS. Suggest you read the archives of the list for all tips and caveats.
Kai
On Tue, Nov 18, 2008 at 01:20:16AM -0700, Jason Taylor wrote:
Hello Kai:
what don't you use http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU and related links instead of howtoforge ?
Tru
Tru Huynh wrote on Tue, 18 Nov 2008 09:41:10 +0100:
what don't you use http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU
This tutorial is much more complicated than using virt-install. There is no need for "installation kernels" and such. You just run virt-install and off you go.
Kai
Kai Schaetzl wrote:
Tru Huynh wrote on Tue, 18 Nov 2008 09:41:10 +0100:
what don't you use http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU
This tutorial is much more complicated than using virt-install. There is no need for "installation kernels" and such. You just run virt-install and off you go.
yeah, its a bit odd that we dont have a libvirt/virttools based howto. Perhaps something to take up.
Jason, I'm surely not going to read the whole tutorial. Tell what exact virt-install command you used and any preparation steps if you did any. (e.g. what did you install to get xen on the system.)
Kai
Kai:
I used yum to install xen and xen-kernel I then edited the grub config and rebooted the server. Using uname -r I verified I was in the right kernel.
I proceeded to use virt-install (and later virt-install --nographics and virt-install --vnc) and none of them will install the guest. It always fails saying that there is no console and to reconnect.
Using xm console ## I try to connect to the console but am given the following error in the qemu log:
qemu: the number of cpus is 1
*** image /local/domain/0/backend/vbd/5/768 format raw driver
0x80e7940
*** image /local/domain/0/backend/vbd/5/5632 format raw driver
0x80e7940 Watching /local/domain/5/logdirty/next-active
Could not initialize SDL - exiting
-----Original Message----- From: centos-virt-bounces@centos.org [mailto:centos-virt-bounces@centos.org] On Behalf Of Kai Schaetzl Sent: Tuesday, November 18, 2008 3:34 A To: centos-virt@centos.org Subject: Re: [CentOS-virt] Need Help with Xen Please
Jason, I'm surely not going to read the whole tutorial. Tell what exact virt-install command you used and any preparation steps if you did any. (e.g. what did you install to get xen on the system.)
Kai
Jason Taylor wrote:
Kai:
I used yum to install xen and xen-kernel I then edited the grub config and rebooted the server. Using uname -r I verified I was in the right kernel.
I proceeded to use virt-install (and later virt-install --nographics and virt-install --vnc) and none of them will install the guest. It always fails saying that there is no console and to reconnect.
When you connect to the Centos server from your remote console you said before that you're using ssh. Is this from another Linux system? You need to ensure that you have access to your local graphical interface from the remote server i.e. that you have a valid DISPLAY variable set. If "echo $DISPLAY" returns an empty string then maybe you just need to do "ssh -X centos_server" when connecting so that ssh will forward the X11 back to your display. Then virt-manager should work.
Then again I might be misunderstanding the problem.
Brett
On Tue, Nov 18, 2008 at 6:41 AM, Brett Worth brett@worth.id.au wrote:
Jason Taylor wrote: When you connect to the Centos server from your remote console you said before that you're using ssh. Is this from another Linux system? You need to ensure that you have access to your local graphical interface from the remote server i.e. that you have a valid DISPLAY variable set. If "echo $DISPLAY" returns an empty string then maybe you just need to do "ssh -X centos_server" when connecting so that ssh will forward the X11 back to your display. Then virt-manager should work.
Sometimes ssh -Y works when ssh -X doesn't. Over time I've started using ssh -Y as it always works.
If the server is setup correctly, it will not allow you to ssh as root, you'll need to ssh -Y as yourself and then su -. When you use the su command you might loose the DISPLAY variable, in this case simply re-establish it and all should work.
If you workstation is Linux, you have an X-Display running. If it is Windows, you can use Cygwin as your X-Server.
Brett
You just need a shell for running virt-install and attach to the xen console, no X.
Kai
Brett:
Thank you for your help. It has been a few days since I was able to give this a try. However I installed Cygwin on my Windows desktop and SSH'd to the headless machine. I then ran virt-install without the graphics support. Doing this I was able to get past where it was stuck before.
I get the CentOS menus for selecting language and then it asks me to configure the IPs. I will only be using IPv4 so I disabled IPV6. However whenever I tell it to use DHCP it hangs forever and I end up having to do a xm destroy and recreate the guest.
Can anyone suggest what the next course of action would be? The server has a single physical NIC and 1 IP. Will I need to request an additional IP address to use with the new guest I create?
Thanks.
-----Original Message----- From: centos-virt-bounces@centos.org [mailto:centos-virt-bounces@centos.org] On Behalf Of Brett Serkez Sent: Tuesday, November 18, 2008 4:58 A To: brett@worth.id.au; Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Need Help with Xen Please
On Tue, Nov 18, 2008 at 6:41 AM, Brett Worth brett@worth.id.au wrote:
Jason Taylor wrote: When you connect to the Centos server from your remote console you said
before that you're
using ssh. Is this from another Linux system? You need to ensure that
you have access to
your local graphical interface from the remote server i.e. that you have a
valid DISPLAY
variable set. If "echo $DISPLAY" returns an empty string then maybe you
just need to do
"ssh -X centos_server" when connecting so that ssh will forward the X11
back to your
display. Then virt-manager should work.
Sometimes ssh -Y works when ssh -X doesn't. Over time I've started using ssh -Y as it always works.
If the server is setup correctly, it will not allow you to ssh as root, you'll need to ssh -Y as yourself and then su -. When you use the su command you might loose the DISPLAY variable, in this case simply re-establish it and all should work.
If you workstation is Linux, you have an X-Display running. If it is Windows, you can use Cygwin as your X-Server.
Brett _______________________________________________ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Jason Taylor wrote:
Can anyone suggest what the next course of action would be? The server has a single physical NIC and 1 IP. Will I need to request an additional IP address to use with the new guest I create?
Jason,
AFAIK you will need another IP address for the VM. This can be done either via DHCP or hard wired in the configuration file.
When you start the xend the python scripts rename your physical ethernet interface to from eth0 something like peth0. Then a software bridge is created (br0) and the peth0 device is attached to one of its virtual ports. Then one of the virtual ethernet devices (veth0) is configured to have the same IP/netmask/broadcast etc as the peth0 device originally had when it was eth0. This interface is also attached to the br0 device.
From then on your VM's interfaces are also attached to this br0 device. Think of this
bridge as a switch. The VM's network connection is totally external to the Dom0's network interface so need to be treated as such. With some scripting you could create another bridge device (e.g. br1) and use either Dom0 or a VM as a masquerading gateway device but that is left as an exercise for the reader. :-)
Brett
Brett Worth wrote:
Jason Taylor wrote:
Can anyone suggest what the next course of action would be? The server has a single physical NIC and 1 IP. Will I need to request an additional IP address to use with the new guest I create?
Jason,
AFAIK you will need another IP address for the VM. This can be done either via DHCP or hard wired in the configuration file.
Domain 0 can NAT for guest domains.
With some scripting you could create another bridge device (e.g. br1) and use either Dom0 or a VM as a masquerading gateway device but that is left as an exercise for the reader. :-)
... or just use vif-script vif-nat in xend-config.sxp.
On Thu, Nov 27, 2008 at 3:52 AM, Jason Taylor cto@hostbigger.com wrote:
Brett:
Thank you for your help. It has been a few days since I was able to give this a try. However I installed Cygwin on my Windows desktop and SSH'd to the headless machine. I then ran virt-install without the graphics support. Doing this I was able to get past where it was stuck before.
Glad that worked for you. Just to be clear, if you use 'ssh -Y target', you can use the graphical virt tools, I do this all the time.
Brett
Jason Taylor wrote on Tue, 18 Nov 2008 03:47:09 -0700:
I proceeded to use virt-install (and later virt-install --nographics and virt-install --vnc) and none of them will install the guest. It always fails saying that there is no console and to reconnect.
Ok, sorry, I expected to get a complete virt-install command line where I could derive the OS you want to install from. My mistake. You want to run virt-install without any parameter and answer all the questions. In that case I need to ask what OS you want to install. And, although you don't want to, have a look at man virt-install and then try an install that uses the command -line parameters instead of asking questions.
Also, earlier you wrote:
Xend does start and I can do everything listed in the tutorial until I get to the virt-manager part.
So, is your problem now with virt-install or with virt-manager? Does your VM get created? Can you start it with "xm create <name of vm>"? Do you see it running in "xm list"? The main point here is that it's not clear from the beginning if virt-install cannot connect to the console and thus you cannot install the OS or if it all creates just fine and you later cannot attach to the running domU console.
Kai
-
Brett Serkez -
Brett Worth -
Caitlyn O'Hanna -
Christopher G. Stach II -
Jason Taylor -
Kai Schaetzl -
Karanbir Singh -
Michael Hall -
Tru Huynh