Re: disk backups

["Oliver Elphick" <olly@lfix.co.uk>]

Ferdinand Schinagl wrote:
  >Hi wizards,
  >
  >is it somehow possible to save a complete disk structure via a net
  >booted system. I guess I have at least to do the(re-)partitioning by
  >hand. I especially think about some windows based  clients which I want
  >to quickly repair in case of "emergency". Therefore, I'd like to install
  >the system, all the apps and stuff and generate an image of the harddisk
  >partitions or even the whole disk(s).
  >
  >Is there anything like this possible with linux at the moment? I know
  >that there are also (commercial) solutions available (one product is
  >called "ghost" or something like that, I do not remember the name
  >anymore).
 
I have chosen to use /dev/hda2 in these examples; change this to the
appropriate device.  If you save a disk or partition like this, you have
to restore onto a disk or partition of exactly the same size.


If you are wanting to save an entire partition or disk across a network,
a possible method is this, or some variation on it:

  dd if=/dev/hda2 bs=32k | rsh remotehost 'dd bs=32k of=/path/to/save_file'

I chose a 32k blocksize to suit disk access, but perhaps you would get
better performance from a blocksize chosen to suit your network package
size.  

rsh is a security problem, but I think you can do something similar with
ssh

Another way is to NFS-mount remotehost's partition and do:

  dd if=/dev/hda2 bs=32k of=/nfs/mounted/partition/save_file

Whichever way you do it, you want to make sure that the partition on
/dev/hda2 is not mounted while you are dumping its physical device, or
you could save it in a corrupt state.  Similarly, do not restore onto a 
mounted partition.


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Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
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