Re: [Xen-users] Xen 3.4.1: pygrub Error: Boot loader didn't return any data!

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Thu, Dec 31, 2009 at 1:46 PM, Gerry Reno <greno@xxxxxxxxxxx> wrote:
>> At this point it's probably easiest to just create another virtual
>> disk with one primary partition, and copy the contents of the original
>> /boot there. It's A LOT easier compared to messing up with existing
>> partition table. Your domU config should then look something like this
>>
>> disk = [ "tap:aio:/var/lib/xen/images/CLOUD-CC-1-boot.img,xvda,w",
>> "tap:aio:/var/lib/xen/images/CLOUD-CC-1.img,xvdb,w" ]
>>
>
> If I do this then maybe I can straighten the original partition table out;
> remove the last two partitions and create a primary active partition for
> /boot.

If you want to use a new disk image for /boot, then yes, the disk
image only need one small partition. You can still use LVM from the
orginal disk -- no need to migrate/copy that.

If you want to modify the existing partition table manually, BE
CAREFUL. fdisk uses cylinders as unit by default, so you should switch
to sectors. Here's an example:

# fdisk -l /dev/xvda

Disk /dev/xvda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1               1        1000     8032468+  8e  Linux LVM
/dev/xvda2            1001        1305     2449912+   5  Extended
/dev/xvda5   *        1001        1305     2449881   83  Linux

# fdisk -lu /dev/xvda

Disk /dev/xvda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1              63    16064999     8032468+  8e  Linux LVM
/dev/xvda2        16065000    20964824     2449912+   5  Extended
/dev/xvda5   *    16065063    20964824     2449881   83  Linux

Now if you recreate the partition table using cyulinders as unit, the
Linux partition will start on the wrong sector. It will be unusable.
However if you use sectors as unit (fdisk -u) you can recreate the
partition table to be like this

# fdisk -lu /dev/xvda

Disk /dev/xvda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *    16065063    20964824     2449881   83  Linux
/dev/xvda2              63    16064999     8032468+  8e  Linux LVM

Partition table entries are not in disk order

pygrub can work with that.

-- 
Fajar

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