Re: [rdiff-backup-users] Safe to mirror backup dir with rsync?

[Engel Sanchez]

Hi Alex. My understanding could be wrong, but this is the scenario that I'm 
trying to avoid:

1) Machine 1 has the original data and backs it up locally to /backup
2) Machine 2 rsyncs /backup to local /backup every day
3) Machine 2 is rsyncing /backup, and right then machine 1 dies for good (fire, 
flood, apocalypse)

At that point in time, machine 1 is dead and /backup in machine 2 is not a 
valid rdiff-backup directory, so you can't restore your data from it anymore.  
If Machine 2 was instead using rdiff-backup on the original sources, /backup 
would have an incomplete backup, but previous data would not be lost, so you 
can restore from it even if it was interrupted.

 Engel A. Sanchez


“Do what you love to do and give it your very best. Whether it's business or 
baseball, or the theater, or any field. If you don't love what you're doing and 
you can't give it your best, get out of it. Life is too short. You'll be an old 
man before you know it.”


http://engelsanchez.net



----- Original Message ----
From: Alex Samad <address@hidden>
To: address@hidden
Sent: Wed, December 23, 2009 6:32:37 PM
Subject: Re: [rdiff-backup-users] Safe to mirror backup dir with rsync?

On Wed, Dec 23, 2009 at 01:58:30PM -0800, Engel Sanchez wrote:
> Thank you all for your suggestions!  I'm going to go with the solution of 
> doing cascaded rdiff-backups both pointing at the source directories and 
> without rsync and simply spreading the cron jobs to avoid touching the 
> sources while they are updated (the sources are hot copies of a couple of 
> databases and a subversion repo).  Using rsync and risking leaving the remote 
> backup in a bad state didn't seem like a great idea to me. (Say rsync's 
> connection breaks and original server fails before next backup). At least 
> rdiff-backup can deal with a partially updated backup if also done by 
> rdiff-backup.  

strange for the same reasons I have used rsync - I can capture when it
fails and restart and it doesn't need to roll back it continues where it
left off. rdiff-backup has to unroll and then restart so for a 2 hour
backup that fails in the last 10 min, you will need to do another 2
hours of backup with rdiff-backup and only 10 min with rsync....

to stop the corruption problem right now I use semaphores around my
backup scripts to stop certain things happening at the same time :)

Alex

> 
>  Engel A. Sanchez
> 
> 
> “Do what you love to do and give it your very best. Whether it's business or 
> baseball, or the theater, or any field. If you don't love what you're doing 
> and you can't give it your best, get out of it. Life is too short. You'll be 
> an old man before you know it.”
> 
> 
> http://engelsanchez.net
> 
> 
> 
> ----- Original Message ----
> From: Alex Samad <address@hidden>
> To: address@hidden
> Sent: Wed, December 23, 2009 4:13:16 PM
> Subject: Re: [rdiff-backup-users] Safe to mirror backup dir with rsync?
> 
> On Wed, Dec 23, 2009 at 12:52:03AM +0100, Cybertinus wrote:
> > Hello,
> > 
> > I'm using rdiff-backup to create the backups of my directories. It all
> > goes to /backup, which is a external harddrive. Then I'm using rsync to
> > mirror everything to /backup_sync, which is a second external harddrive.
> > This one is encrypted and I move it to an external location once a week
> > (and the disk from the external location then becomes the sync disk ;)
> > ). I'm using this strategy because when I swap the sync disks, they are
> > disconnected from my computer for a day. Some data I'm backing up every
> > hour, so I need a external drive at my computer at all times.
> > This system is working perfectly for me. The only thing I would
> > recommend is to prevent running rdiff-backup at the same time as rsync.
> > To prevent that your mirror is accidentally destroyed, because you would
> > by rsyncing incomplete rdiff-backup data. I haven't build in this
> > precaution in my backupscripts yet. For the time being I'm preventing it
> > from running at the same moment by choosing the correct times in my
> > cronjobs.
> 
> Hi
> 
> I am doing something similar.
> 
> local machine rdiff-backup to /backup (lvm partition).
> then a rsync to the local backup server and at the same time a rsync to
> an offsite location - via adsl.
> 
> I do this because my initial rdiff-backup can happen quickly and cause
> the lest disruption - if the source is on a lvm I can take a snapshot
> and use that but not all the sources are.
> 
> I have come across one problem, if the over adsl takes too long the
> rdiff-backup destination on the local machine can change thus giving you
> a non in sync backup offsite.
> 
> There is another thread asking for a tool to lock the destination to
> prevent this
> 
> Alex
> 
> > 
> > Cheers,
> > Cybertinus
> > 
> > On 23/12/09 00:03, Gavin wrote:
> > > Hi Engel,
> [snip]
> 

-- 
"Bureaucracy is the enemy of innovation."
        -- Mark Shepherd, former President and CEO of Texas Instruments