[Box Backup] Client on laptop questions/suggestions

[Ben Summers]

On 21 Jun 2004, at 12:45, John Pybus wrote:

> [Ben, I figured these thoughts would be better mentioned to the list 
> than in my reply to you]
>
> I am setting up boxbackup to make encrypted backups of frequently 
> disconnected laptops, to a server that is then part of a larger 
> scheduled backup regime,

You should note that the server currently stores full copes of each 
version of a file, even if it was uploaded using the rsync-like 
feature. At the moment, transport efficiency has been my greatest 
concern (as bandwidth is more expensive than discs), however, it's due 
to be addressed soon, along with marks and archive options (the biggest 
current deficiency of the system).

>  and have one or two questions about client use:
>
> My current plan is to use the client in snapshot mode, and then rely 
> on cron and some shell scripting to only attempt a backup if connected 
> to the server's local network.  I don't want a machine at home on 
> metered connections, or connected via meagre shared links at 
> conferences, to use bandwidth without user intervention.  It might be 
> a useful feature if bbackupd could run in lazy mode but only attempt a 
> backup if on a particular subnet.

How about I add a feature which runs a script before every potential 
sync, and if the script says "no" doesn't do the sync? Or, it returns 
"now" to do it now, or a number of seconds to wait before considering a 
sync again.

>
> Given that I'm running in snapshot mode, and that some of the machines 
> in question are not overly endowed with RAM, is it possible for 
> bbackupd to be started as required and then exit, rather than remain 
> running for long periods of time when it won't be doing anything?

If you do this, you will lose the RAM based database of the states of 
directories on the server. This means that when it connects again, it 
will read the contents of every directory on the server, rather than 
just the ones it knows have changed. This may not be a problem for you.

I do mean to write some code to serialise this state to disc, and then 
have a daemon-less mode for snapshot syncs. Not difficult, it's even 
written with this in mind. However, no-one's requested it yet, and I 
haven't needed it.

>  If not perhaps bbackupctl could be adjusted to operate in this mode?
>
You could write a script which runs the daemon, does bbackupctl sync, 
waits for the file /var/bbackupd/last_sync_end to be touched (or 
created if you delete it as first thing in the script), then kills the 
daemon.

Ben