Re: [Xen-users] How to change VM from para-virtualization to full-virtualization?

[Jerry Gao <jerry.gao@xxxxxxxxxxxx>]

Hi Alexandre,

Thank you very much for you reply. Actually, I'm not an expert of Xen, so...

About the 3rd step:
"3. Re-write your .cfg file within Dom0 to make it start the DomU as HVM."
Which .cfg file are you referring to? Is there an example of it? Thanks.

About the 4th step:
"4. Install the boot loader into you DomU storage's MBR, watch the kernel 
command line for root= parameter. I would recommend doing this booting the HVM 
DomU with a LiveCD, Knoppix or systemrescuecd should do fine."
Are you talking about to change the menu.list file of grub? Would you please 
help to give me more details about this step.

About the 5th step:
"5. Modify your /etc/fstab to reflect the change of the block devices naming 
(from /dev/xvdaN to /dev/hda or whatever)."
My previous VM is created on a virtual hard disk like /dev/drbd00. Then do I 
still need to change the storage device name?

Thanks,
Jerry
ECN: (887) 17175
Phone: +86 10 6439 4175


-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxx] 
On Behalf Of Alexandre Kouznetsov
Sent: Wednesday, October 31, 2012 1:30 PM
To: xen-users@xxxxxxxxxxxxx
Subject: Re: [Xen-users] How to change VM from para-virtualization to 
full-virtualization?

Hi.

El 31/10/12 10:27, Jerry Gao escribió:
> I've created a domU in para-virtualization. But now I need to change 
> it to full-virtualization.
> Is it possible to upgrade/change the VM virtualization mode without 
> impact the OS+App in the VM? And How?

Yes, it is possible. Can be a bit tricky because there are many details to take 
care of, even if each of this details is trivial by itself.
 From DomU's point of view, the change will affect the kernel used in the DomU, 
the boot loader and the storage devices naming.

This is a small overview of what need to be done:
1. Make sure your DomU system has a regular kernel and a boot loader installed.
2. Make sure the storage is presented to the DomU as a partitioned block 
device(s).
3. Re-write your .cfg file within Dom0 to make it start the DomU as HVM.
4. Install the boot loader into you DomU storage's MBR, watch the kernel 
command line for root= parameter. I would recommend doing this booting the HVM 
DomU with a LiveCD, Knoppix or systemrescuecd should do fine.
5. Modify your /etc/fstab to reflect the change of the block devices naming 
(from /dev/xvdaN to /dev/hda or whatever).

Word of advice, in many cases it's preferable to re-install the guest system, 
then move data and configs. This way you get a more predictable result.

--
Alexandre Kouznetsov


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