Disaster Recovery and Rsync (was [lug] Commercial rsync service?)

[David L. Anselmi]

Sigh... (and sorry for the first copy of this, my keyboard had a seizure)

Siegfried Heintze wrote:
> It sounds like we are back on the old disaster recovery topic again...
> 
> What are some favorite ways of using rsync with a remote repository
> accessible over the public internet for the purposes of disaster recovery?

No, we're not back on disaster recovery.  WAN backup doesn't scale for
most people so it isn't done. See:

http://catless.ncl.ac.uk/Risks/24.15.html#subj11

for one real life example.

I would suggest that you implement every disaster recovery architcture 
you can think of, try them out, and write a paper on the pros and cons 
of each.  You could present your paper at a conference (probably 
several).  You'd have fun, meet lots of interesting people, and no 
longer be fixated on disaster recovery ;-)

> (1) Would you only use rsync on directories you are working in?
> 
> (2) Would you daily rsync everything including...

No.  This is what system backups are for and rsync over a WAN is not a 
system backup.  If you're talking about disaster recovery you're talking 
about system backups.  So you use backup software that handles all the 
details for you.

> (3) How do databases work?

They do their own backups and you put those on tape (or your backup 
media of choice).  You don't back up their data files and you don't take 
the DB down to do it.

> (4) What about links? Creators of linux distros love links. Does rsync
> properly reconstruct hard and soft links?

Ask man, it knows.

> would rsync be smart enough to find that sub directory in the remote  repository

Yes.  But try it and see.  It's smart enough but maybe not as smart as 
you want.

> Can rsync simply bypass the NTFS file system and do block level restores?

Yes but I'm not a fan of imaging for backups.  Too cumbersome or brittle.

And if this isn't provocative enough, I think you're wrong about distro 
developers loving links. ;-)

Dave