Rsyncing of block devices to a remote file

[Dave Dykstra]

I'm not sure why it would really need to know the size, but given that
it wants it, can you open the file and lseek to the end of it?

- Dave Dykstra

On Thu, Jan 23, 2003 at 09:17:04AM +0100, David Heremans wrote:
> Hello,
> 
> I'm looking for some assistance in modifying the rsync code
> 
> Situation: I used to back-up some of my (unmounted NTFS) disk partitions
> remotely using the following shells construct:
> dd if=/dev/hda1 | gzip | ssh me at backupmachine 'cat >
> /backup-dir/hda1-backup.gz'
> 
> But now I want to use rsync for this, since transfering 10 gig takes a litle
> to long if a file of a few kB has changed :-). I looked trough the archive
> and found an old mail talking about the same problem, and a response
> explaining the problem of writting to a block device (since rsync writes a
> copy file and then moves it over the original). But the same mail also said
> that reading from it should be trivial, so I set out trying to implement
> this.
> 
> So I created a '--read-block-file' option in options.c and avoided the
> 'skipping non regular file' message in generator.c
> By altering all this the receiver is ready to get the data, but in the flist
> structure it still says that '/dev/hda1' is still a devicefile 
> and that the size is 0, and so the sender does send over zero bytes
> 
> Now here is the problem : How do I get the size of partition in this
> datastructure ? Or more generique, how would I handle this for /dev/fd0,
> since you can insert 1.44MB disks or 720kB disks ?
> 
> Anybody else tried to read blockdevices over rsync already ?
> 
> After all, sending the data of a block device doesn't seem to be as trivial
> as the archived mail sugested :-)
> 
> David 
> 
>