rsync - May 2008 - How to backup files without destroying the destination?!

Hello List,

i would like to copy/mirror/rsync the backup files from ServerA to ServerB.
Since i must assume that ServerA is hacked (public server with a few 
services), i would like to "pull" the files to ServerB (save server
with
no services).

That means i do something like: rsync -avz ServerA:/backup ServerB:/backup

IF ServerA gets hacked and the files get zeroed out (every file has 
rubbish or 0 bytes), then i would also destroy my files on my 
destination ServerB.

Whats a good way to prevent this?
Any ideas are welcome :)

Cheers,
Mario

On Fri, 2008-05-30 at 21:22 +0200, ml wrote:
> i would like to copy/mirror/rsync the backup files from ServerA to ServerB.
> Since i must assume that ServerA is hacked (public server with a few 
> services), i would like to "pull" the files to ServerB (save
server with
> no services).
> 
> That means i do something like: rsync -avz ServerA:/backup ServerB:/backup
For a pull, you would run the command on ServerB and leave out the
destination hostname:

?rsync -avz ServerA:/backup /backup
> IF ServerA gets hacked and the files get zeroed out (every file has 
> rubbish or 0 bytes), then i would also destroy my files on my 
> destination ServerB.
> 
> Whats a good way to prevent this?
Instead of just one backup, keep a series of backups on ServerB and
sanity-check them periodically.  That way, if ServerA is hacked, you'll
have a period of time to notice and recover from a good backup.  To save
space, you could use a tool that hard-links unchanged files; my personal
favorite is rsnapshot ( http://www.rsnapshot.org/ ).

Matt
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On Sat, 2008-05-31 at 08:57 +0200, ml wrote:
> > Instead of just one backup, keep a series of backups on ServerB and
> > sanity-check them periodically.  That way, if ServerA is hacked,
you'll
> > have a period of time to notice and recover from a good backup.  To
save
> > space, you could use a tool that hard-links unchanged files; my
personal
> > favorite is rsnapshot ( http://www.rsnapshot.org/ ).
> >   
> So you are basically saying i need to backup my backups? :)
Perhaps you could think of it that way, but I'm not suggesting recopying
any data after it is already on ServerB.  I'm just suggesting copying
ServerA's data to a different destination on ServerB each time so that,
if ServerA goes bad, you'll still have a destination made when it was
good.  To prevent the space usage on ServerB from growing indefinitely,
you could periodically check the latest destination for any corruption
and, if it is good, delete all the other ones.

Matt
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Hello,
> To prevent the space usage on ServerB from growing indefinitely,
> you could periodically check the latest destination for any corruption
> and, if it is good, delete all the other ones.
... or you could try dirvish (www.dirvish.com): for every new backup it
creates a directory where every file which hasnt changed since the last
backup is just a hard link to the old one. This way a backup hierarchy costs
you almost no extra disk scpace.

-- 
Greets,
Leonid Chaichenets.