CentOS - Dec 2007 - Resizing a Xen DomU disk image

Hello Mailing List!

A quick question.  Has anyone gotten a resize (in my case grown) a Xen
DomU disk image?

Here is the procedure I have followed:

1.  Install a DomU using virt-install
	Customize xvda to be all one partition ext3
2.  On Dom0:
	dd if=/dev/zero bs=1G count=1 >> <my_disk_image>
	ll -h (Image is now 1GB larger)
	xm create <DomU>
    On DomU:
	df -h (Size has not changed)
	shutdown -h now
    On Dom0:
	e2fsck -f <my_disk_image> (Errors Bad Magic...)
	resize2fs -f <my_disk_image> (Errors Bad Magic...)
	xm create <DomU>
    On DomU:
	df -h (Still reports old size)

I am assuming that because resize2fs didn't run that the DomU doesn't
know about the additional space.

Thanks in advance!

On Dec 19, 2007 7:26 PM, Matthew Lind <mlind at nhctc.edu>
wrote:
> Hello Mailing List!
>
> A quick question.  Has anyone gotten a resize (in my case grown) a Xen
> DomU disk image?
>
> Here is the procedure I have followed:
>
> 1.  Install a DomU using virt-install
>         Customize xvda to be all one partition ext3
> 2.  On Dom0:
>         dd if=/dev/zero bs=1G count=1 >> <my_disk_image>
>         ll -h (Image is now 1GB larger)
>         xm create <DomU>
>     On DomU:
>         df -h (Size has not changed)
>         shutdown -h now
>     On Dom0:
e2fsck works only on device, but yuo can creat a loop device using losetup

someting like

losetup -f <my_disk_image>

now you can mount, e2fsck or resize /dev/loop0
>         e2fsck -f <my_disk_image> (Errors Bad Magic...)
>         resize2fs -f <my_disk_image> (Errors Bad Magic...)
then delete the loop device

losetup -d /dev/loop0

regards
>         xm create <DomU>
>     On DomU:
>         df -h (Still reports old size)
>
> I am assuming that because resize2fs didn't run that the DomU
doesn't
> know about the additional space.
>
> Thanks in advance!
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
>


-- 
Alain Spineux
aspineux gmail com
May the sources be with you

Thanks for the reply.  However, when I performed a:

losetup -fv <my_disk_image>

I still received the following error:
e2fsck 1.39 (29-May-2006)
Couldn't find ext2 superblock, trying backup blocks...
e2fsck: Bad magic number in super-block while trying to open /dev/loop0

The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate
superblock:
    e2fsck -b 8193 <device>

And here is the output from resize2fs:
resize2fs 1.39 (29-May-2006)
resize2fs: Bad magic number in super-block while trying to
open /dev/loop0
Couldn't find valid filesystem superblock.


Thanks again!