Re: rsnapshot preliminaries

On Fri, Aug 11, 2006 at 11:03:32AM +0200, Reinhard Moeller wrote:

> I am new to backing up with rsnapshot and arguing whether
> my question is too simple.

Please join the rsnapshot-discuss mailing list at
https://lists.sourceforge.net/lists/listinfo/rsnapshot-discuss.  I've
CCed the list with my answer.

> What do I need to have or to install before I can restore a
> completely crashed system? Is it sufficient to memorize the
> disk layout and some system parameters in order to install
> a mini- system, install a new snapshot environment and then
> restore the whole system from (i.e.) a remote disk or system?

Yes.  For all of my machines I have a file sitting on the backup server
describing their disk layout, which filesystems are on which devices,
how big they are, what filesystem type they are etc, and exactly which
version of the OS is installed.  I have CD image files for the various
OSes on the server too so I don't have to hunt around the interweb for
unobtainium old versions.

Once I've got the right disk layout and OS and got the filesystems
mounted, I install the minimum necessary packages (perl, rsync, ssh
rsnapshot), stop just about all the running processes, and restore
over the network.  Some OSes will need some custom twiddling at this
point - for example, on Linux you might re-run lilo to make sure that
the boot record is pointing at the right place on the disk for the
kernel file you just restored - before a reboot.

To restore I just rsync from the appropriate backup directory -
generally the most recent - with all the options for restoring mode,
owner, group, timestamps and everything else.  If you've used any
unusual options like -S or -H when taking your backups, don't forget to
use them when restoring too!  You'll be ableto check what they were
because your rsnapshot.conf will, of course, be in your backups.  You
*do* backup your config files, right? :-)

An alternative to installing the OS and then restoring over the top of
it might be to run from a CD and RAM disk and mount your target root
fs and all the others in a sub directory and restore there.  Again, don't
forget to run lilo!

> Is there a "quickstart" procedure that allows me to store
> all relevant configuration?

rsnapshot only handles files, so anything outwith that - boot records,
the precise location of files on the disk, partitioning - is not handled.

All of the above assumes, of course, that your backups are on a seperate
machine from that which needs restoring.  If not, then you won't need to
install anything networky like ssh (of course) but will have to
additionally mount your backup drive (and perhaps configure RAID drivers
if your backups live on a RAIDed volume) before restoring.  I have the
configuration of my backup server written down on a piece of paper.

> BTW. My system is Debian Linux on Digital Alpha DS 10

OK, where I said lilo above, I think you'll need to fiddle with milo or
srm.  Otherwise it should all be the same AFAIK.

Of course, you should test your restore procedure before coming to rely
on your backups!

-- 
David Cantrell | top google result for "internet beard fetish club"

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