Re: [Xen-users] Guest O/S Questions

[Anthony Liguori <aliguori@xxxxxxxxxx>]

Marcus Brown wrote:

> > You're right.  fdisk (and AFAIK, modern partitioning tools) prefer to
> > start partitions on the first cylinder boundary.  The assumption here is
> > that each cylinder contains 63 sectors.
> >    
> OK, but why skip this cylinder?
> If you are creating an image with multiple partitions won't you need to
> keep the partition table intact?
>  
Ok, let's back track a little.  The dd command I suggested is only 
useful for extracting the first partition from a partitioned disk image 
assuming that the first partition occupies all of the remaining disk 
space and starts on the 63rd sector.
It just so happens that if you partition a disk with only a single 
partition, with most partitioning tools, they'll always put the first 
partition on the 63rd sector.
I think the reason it chooses that sector is that it is the first sector 
on the second cylinder and it reserves the rest of the first cylinder 
for other uses (such as extra space for a boot loader).
If you're just exporting the whole disk, you don't need to do this 
command.  You would only use this command if you were trying to export a 
file system image as a partition (as hda1, hda3, etc.).
Regards,

Anthony Liguori

> Marcus.
>
>  

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