Re: [Xen-users] migrate from physical disk problems in xen

[Paul Stimpson <paul@xxxxxxxxxxxxxxxxxxxx>]

Hi Adam,

On 18/01/13 18:31, Adam Goryachev wrote:
> I've been trying to migrate a win nt 4 machine to a xen domu for the past few 
> months with no success. However, on my current attempt, the original hardware 
> no longer boots, so I'm trying to resolve the issues with xen properly, or else 
> take a long holiday...
On one of our Windows XP installs in a far off place, we found that the 
HAL that shipped on our Windows disc wasn't virtualisation-friendly. 
This was on VMWare (not Xen) so it may not apply but we had to get a 
special version of XP with a different HAL.
> Anyway, the physical machine had a 9G drive (OS drive), a 147 G drive (not in 
> use) and a 300G drive (all SCSI Ultra320 on the same SCSI controller)
From here on it, I will call the 9GB drive "sda", the 147GB "sdb" and 
the 300GB "sdc" - Please adjust anything I say if your system is different.
> Everytime, I've booted linux, used dd to image the original 2 drives (ignored 
> the 147G drive), and written each image with dd to an LV
Are you dd-ing the Windows partition or the whole drive into the 
container file? I think you will get better results with the whole drive.
> This is exported by iscsi to xen
>
> The c: works fine, and I can boot properly in VGA mode (safe mode) but the 300G 
> drive always shows as corrupt. I've now upgraded to win2000 in the VM, and 
> win2000 reports the drive as healthy (hardware) but blank with no filesystem on 
> it.
What are you passing to the VM in the "disk=[]" line please?

Whatever you pass will be interpreted by Windows as a raw drive, so it 
can't just be a partition, it has to have a partition table and MBR too. 
If you just pass a partition, you are likely to see some strange 
partitioning arrangement in Windows Disk management (random size 
partitions/free space chunks) and, in the file manager, you will see no 
files.
The disk line should probably pass sdc, rather than sdc1, or you need to 
make a partition table and a partition in it using parted.
> However, on the xen machine, I can use fdisk to see the partition table, kpartx 
> -a to add the partition device in /dev/mapper, and I can even mount the drive 
> in Linux and see all of it's contents.
I would recommend you don't use fdisk in Linux on this kind of task. 
Fdisk has a nasty habit of imposing its own default CHS geometry on 
disks. Like, the other day, it told me the appropriate start sector for 
the first partition on my virtual disc was 2048 when it really should 
have been 63). This can lead to things not matching and may be stopping 
your VM from mounting the machine.
> I suspect the problem is the way windows translates the CHS values of the 
> drive, and so can't see things the same way that NT could on the physical 
> hardware.
May well be due to what Linux fdisk did... I would recommend you try 
parted instead.
> I'm at a complete loss on how to resolve this issue, or what to try/look at. If 
> all else fails I figured to try and create a new 300G drive, format it from 
> win2k, and then somehow transfer the files from Linux into win2k, without 
> losing any of the permissions / etc which I guess will be somewhat challenging.
Some useful commands...

#Create a new partition table in sdc. (change msdos to gpt if needed)
parted -- /dev/sdc mklabel msdos

#Make a single, primary NTFS partition filling the whole drive but don't 
format it (change the sector numbers to match your real disc's partitions)
parted -- /dev/sdc mkpart primary NTFS 63s -1s

Use kpartx -a to load the new pt...

#build an NTFS filesystem in the new partition
mkfs.ntfs -Q -L VOLUME_LABEL /dev/sdc1

Good luck,
Paul.

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