Re: [rdiff-backup-users] Rdiff backup partial transfers

[Andrew Ferguson]

On Feb 9, 2009, at 7:22 AM, Mark Ridley wrote:

> Hi,
>
> The way rdiff-backup works is that if a file is being transfered and  
> the connection is lost, rdiff-backup rolls back the transfer of that  
> file.
>
> If the file is large - for example a database - it can take several  
> hours to completley transfer a file. If the connection gets dropped,  
> the transfer starts again from the beginning.
>
> Is there a way to do partial file transfers, so that the next time I  
> invoke rdiff-backup, it carries on where it left off.
>
> rsync works this way with the --partial option.
>
> is it possible to do this with rdiff-backup?
>
> if not, is this somthing that can be added with a code change - or  
> is there a fundamental reason why it cannot work this way?


Mark,

After the file is transferred once, it does not take very long for  
rdiff-backup to use the rsync algorithm to calculate any changes. As  
long as you are using rdiff-backup in the default configuration (with  
rdiff-backup installed on client & server and running over SSH),  
you'll be fine.

That leaves us with the problem of the first transfer. If you are  
worried about the connection dropping during the first transfer, you  
can use rsync to copy the data to the server, then turn it into an  
rdiff-backup repository with the use of the --force option. I believe  
the Wiki describes this in greater detail.

$ rsync foo rsync://address@hidden/backup
$ rdiff-backup --force foo address@hidden::/backup

then drop the --force option from subsequent rdiff-backup operations.


If you think you'll be creating large files regularly after the first  
backup, then perhaps other users have some creative suggestions. I  
haven't thought about adding this feature (--partial) to rdiff-backup,  
so I don't know how feasible or not it is.


Andrew