Using rsync to syncronize two unmounted disk partitions

Antonio Arauzo Azofra arauzo at
Fri Mar 17 11:54:05 GMT 2006

Hi Wayne,

Thanks for your reply, and thanks to Matthew and Matt too.

Wayne Davison wrote:
> I wonder if someone has written a simple filesystem driver which mounts
> the raw data of a device as though it were a single, big file?  Such a
> solution would allow the use of any normal filesystem tool (including
> rsync) on block-device data.

I seems good idea, but i am not sure if that is necessary, or if it is
easyier to simply use the device as a file with some restrictions. :-?

>>   # rsync /dev/hda8 /dev/hda9
> Using rsync to update the data for two local block devices wouldn't be
> very useful because the incremental-update algorithm would tend to slow
> down the transfer instead of speed it up (the only exception for a local
> transfer is when the write speed for a device is much slower than the
> read speed, and enough of the data matches that the saved write time
> more than makes up for the extra read time).

You are right. I was testing with a misfortunate example and when I saw 
the error I thought it was not possible in general to use devices. I 
have only checked that rsync does not allow a device as source but not 
as destination. Thanks to your message I did a new test, and it seems 
rsyncs allows this:

    rsync <file local or remote> /dev/hda9

I have hanged the device testing to overflow it, but it seems it works. 
(I haven't tested much yet)

   Antonio Arauzo Azofra

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