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

David L. Anselmi anselmi at anselmi.us
Fri Feb 3 15:20:18 MST 2006


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:

> (1) Would you only use rsync on directories you are working in? It then
> becomes your responsibility to remember which directories you have modified
> files in. I've done this for years with zipping directories on CDs but it
> scares me. And if you get hacked you still have to rebuild your system disk.
> (2) Would you daily rsync everything including the /usr/bin, /bin,
> /usr/local/bin, /etc, etc...? I guess you would use the find command to
> exclude stuff in the /mnt directory so you would not include the entirety of
> other devices on other machines.
> (3) How do databases work? Do you have to stop the (for example) MySQL
> deamon while you do the rsync? My guess is definitely. What about the
> subversion or cvs deamons? Could this be a problem if you try to use a
> single rsync command for an entire computer's local storage and it takes a
> long time? It seems to me like you would want to have a lot of short shell
> scripts to run daily so you don't have to shut down all your servers at once
> for the entire duration of the synchronization.
> (4) What about links? Creators of linux distros love links. Does rsync
> properly reconstruct hard and soft links?
> (5) Let us say you initially rsync the entirety of your local storage for a
> software development computer that also doubles as prototyping web site
> server and cvs/subversion repository. Maybe it is Saturday and you know you
> have only altered one file. Could you rsync that directory only and would
> rsync be smart enough to find that sub directory in the remote repository
> instead of having to date compares on all the files for the entirety of your
> local storage?
> (6) I believe someone previously explained that one can boot from a LiveCD
> and use rsync to restore your boot disk and then boot from the boot disk. I
> guess I should give this a try before disaster strikes. To bad this won't
> work for windows (NTFS) paritions (or will it?). Has anyone tried it? Can
> you run rsync on a windows partition? If you were doing it for the purposes
> of rebuilding a boot disk, I think you would want to do this at a block
> level because special files like the windows registery cannot (I believe) be
> simply copied. Sometime ago someone explained to me that they could zip an
> entire Win95 boot disk and restore it with zip and expect to boot, but this
> did not work with NT. I assume this is still true with XP.
> Can rsync simply bypass the NTFS file system and do block level restores?
> Perhaps there is some other utility?
> Thanks,
> siegfried
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