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Re: [Xen-users] Convert physical server to VM



Hi,

remenber, there exist 2 kinds of virtualization in XEN:

- paravirtualization
- full virtualization

we are talking about "full virtualitzation" (unmodified guest) no?

In full virtualization you needs something thats seems a real disc, with MBR, partition table, partitions with corresponding filesystems... the only way that I know to copy all this is with dd command.

What version of Xen are you using? I don't have any file named domUloader.py :S

Regards,

Marc

Chiu, PCM (Peter) wrote:
Thanks, Marc,

This is different from what is described on the Xen V3.0 User's Manual Page 34,
where it shows a selection of root file system files are copied.

Probably there is where it gets wrong.

On the other hand, some of our existing kits are having a root file system being partitioned off a RAIDed storage, so the whole disk (/dev/sda) is in Terabyte large.

I shall your method first, which I believe will also copy the boot block info.
This process will take some time.

Can I also check one thing with you.
My current vm configuration file is a copy of an Suse 10.2 guest configuration.
This contains the following bootloader info:

bootloader = '/usr/lib/xen/boot/domUloader.py'
  bootentry = 'hda1:/boot/vmlinuz-xen,/boot/initrd-xen'

Bearing in mind, the guest Linux VM does not have /boot/vmlinuz-xen and 
/boot/initrd-xen
in its own /boot folder.  Shall I change them to:
  kernel = "/boot/vmlinuz"
  ramdisk = "/boot/initrd"

to reflect the actual kernel and ramdisk residing on the guest /boot folder?

Peter


-----Original Message-----
From: Marc Patino Gómez [mailto:mpatino@xxxxxxxxxxxx] Sent: 23 August 2007 15:25
To: Chiu, PCM (Peter)
Cc: Simon Gao; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Convert physical server to VM

Hi,

the problem is that you only copy the filesystem with tar command. You must 
copy the FULL disc, to do this follow use dd, as I post before

dd if=/dev/hda | ssh root@xxxxxxxxxxxxxxxxx "/bin/dd of=/xen/images/myimage.img"


so the process will be:

1- dd if=/dev/zero of=image.img bs=1M count=4096 (if you have a 4GB HD, if your 
physical HD is 4GB)
   remember, the image must be at least the same size than your original HD)

2- stop old box, and boot with a LiveCD

3- Copy the disc to your XEN server
   dd if=/dev/hda | ssh root@xxxxxxxxxxxxxxxxx "/bin/dd 
of=/xen/images/myimage.img"


Good luck,

Marc

Chiu, PCM (Peter) wrote:
Thanks, Marc, for your speedy response.

I was hoping to set up a guest VM on existing Suse9/10 and Redhat4/5 systems.

Still, I use tar to copy the whole of the root directory tree on a running Linux system into the loop mounted image.

Here are the steps I took:
dd if=/dev/zero of=image bs=1k seek=10240k count=1 mkfs -t ext3 image mount -o loop image /mnt/temp cd /mnt/temp ssh remote "tar -zaxHS -f - /" | tar -zxpf - cd umount /mnt/temp

I then use Yast2 xen to create a guest VM configuration and start it. But it fails with the "Boot loader didn't return any data" error.

I also tried to re-create a vm configuration file by copying a working Suse 10.2 one, but still hit the same fault.

So I suspect something is missing to make the above image to be bootable.

Any idea?

Peter
-----Original Message-----
From: Marc Patino Gómez [mailto:mpatino@xxxxxxxxxxxx]
Sent: 23 August 2007 14:24
To: Chiu, PCM (Peter)
Cc: Simon Gao; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Convert physical server to VM


Hi,

Chiu, PCM (Peter) wrote:
Hi, there,

I am watching this thread with interest.

Marc, can you repeat the actual steps you do to set up Linux guest VMs, especially the ones using 2.4 kernels.

I have tried similar steps you mentioned, apart from the cp -pr /lib/modules into the guest OS disk, but when I start up the guest VM, it complains
If you are going to "full virtualitzed" a linux box you don't need to copy the 
kernel's modules, you will use the unmodified old OS kernel ones, and the old kernel (of 
course).
"boot loader didn't return any data!"
Have you copy the full HD? or only the partition?
It looks like something is missing to turn the root copied file system to be bootable as a guest VM.

Thanks.

Peter
Good luck Peter,

Marc
-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Marc Patino Gómez
Sent: 23 August 2007 12:05
To: Simon Gao
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Convert physical server to VM

Hi,

rsync works great on production enviroments, I had paravirtualized some servers 
with these method:

rsync -ave ssh --exclude=/proc --exclude=/sys --exclude=/dev (if you are using udev) root@runingserver:/ /mnt/newserverimage/

after this:

mkdir /mnt/newserverimages/proc

mkdir /mnt/newserverimages/sys

mkdir /mnt/newserverimages/dev

review your fstab, and copy the kernel modules:

cp -pr /lib/modules/2.6.16-xenU /mnt/newserverimages/lib/modules/

more or less .... this is the way

Also I have full virtualitzed some old GNU/Linux boxes with kernels 2.4, I used 
GNU/Linux live CD on the old box and dd utility:


dd if=/dev/hda | ssh root@xxxxxxxxxxxxxxxxx "/bin/dd of=/dev/vg00/newvserver"

I hope it will be helpfull


Marc

Simon Gao wrote:
Hi,

Anyone has any suggestions on programs, utility or instructions on how to convert a physical server to domU VM?

Thanks,

Simon

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