1  # Stop & backup
   2  xm stop sandbox
   3  cp -a sandbox/ sandbox.bk
   4  
   5  # Verify MD5 sum
   6  md5sum sandbox/disk.img 
   7  4976347006df34843d29c939b5fc3742  sandbox/disk.img
   8  md5sum sandbox.bk/disk.img 
   9  4976347006df34843d29c939b5fc3742  sandbox.bk/disk.img
  10  
  11  # Create a 5Gb temp file
  12  dd if=/dev/zero of=Tempfile bs=1024 count=5000000
  13  
  14  # Append it to the existing image
  15  cat Tempfile >> disk.img
  16  rm Tempfile
  17  
  18  # Resize the partition
  19  resize2fs -f disk.img
  20  
  21  # Check partition & start domU
  22  fsck.ext3 disk.img
  23  xm create -c sandbox.cfg

   1  xm shutdown xyz
   2  mount -o loop disk.img /mnt/os-image/
   3  chroot /mnt/os-image/
   4  
   5  # Do your stuff
   6  
   7  exit
   8  umount /mnt/os-image

Using this key combination on a system having Finnish keyboard mapping you can detach from a xen console.

   1  CTRL + Alt Gr + 9

Xen VM’s support up to three IP addresses. Just give them as parameters when you create the image. There will be one interface within the Xen and the other IP’s are mapped to interface aliases.

   1  xen-create-image ... --ip=10.0.0.44 --ip=10.0.0.45 ...

If you use Xen and get an error “Failed to find an unused loop device” when you try to create a guest then you are probably using disk images and have run out of loop devices. Each guest uses at least two loop devices. Modify (or create) a file called /etc/modprobe.d/local-loop and add this line:

   1  options loop max_loop=64

Use a number suitable for your needs. With 64 loop devices you can run up to 32 guests on your host, assuming you aren’t using loop devices for any other purposes.