[PLUG] A dumb move, so how do I avoid it in the future?

Patrick J. Timlick p.j.timlick at ieee.org
Sun Jan 8 02:15:11 UTC 2012


Sorry to hear of the unintended consequences of removing a backup.  Don't
you just hate it when things like that happen, I do.  One way to avoid
these consequences in the future would be to use the tar program to create
backup archives.  You would save space and you could then remove the whole
archive without those unexpected consequences.   The downsides are tar will
be slower to back up your system, and it will be less convenient to access
to individual files.  Do "man tar" to get started, then google "tar system
backup"  for lots more information.  Good Luck.

-- Pat

On Sat, Jan 7, 2012 at 5:44 PM, Dale Snell <ddsnell at frontier.com> wrote:

> On Sat, 7 Jan 2012 15:11:50 -0800
> website reader <website.reader3 at gmail.com> wrote:
>
> > Okay, I admit that I don't understand symbolic links for files.
>
> A symbolic link is essentially a file that contains the pathname
> of another file.  The OS sees the pointer in the link file and
> proceeds to act on the target.  The advantage to symbolic links is
> that they work between filesystems, which regular hard links
> cannot do.  (A hard link is simply a directory entry, so it can't
> cross filesystem boundaries.)
>
>
> > Here's what I did, I backed up all the files on my Ubuntu Lucid linux
> > to a backup drive using the commands
> >
> > rsync -av /folder /backupfolder  or cp -ruvp /folder /backupfolder
> >
> > This seems to work quite well, with the exception of the /dev and
> > /proc and /sys folders contents which I guess I don't really care
> > about anyways.
> >
> > Here's what happened yesterday.
> >
> > I erased the files in the /home/me folder on the backup drive, in
> > preparation to do a "fresh" clean copy onto the backup.
> >
> > Since I had previously backed up all the folders from / (root) I
> > decided to get a fresh copy of those folders also to my backup drive,
> > so I started erasing the file folders on the backup drive starting
> > with the /bin folder.
> >
> > Eventually I erased the files in the /lib area on the backup drive.
> > Okay, no apparent problems.
> >
> > Then I erased the files in the /lib32 area on the backup drive and
> > then the /lib64 area, which was a link pointing back to the /lib area.
> >
> > Suddenly I lost my /sbin and /bin commands.  The whole system became
> > inoperable and I couldn't do anything at all.  I had to do a manual
> > reset to reboot, which failed, of course.
>
> This sounds like a typo somewhere.  The ../backupfolder/lib64 link
> to ../backupfolder/lib should not have affected your working
> system.  I've done that same sort of thing, it's all too easy.
>
>
> > I had to rebuild the Ubuntu 10.04 Lucid from scratch and restore all
> > my files and programs again, which became a 7 hour ordeal.  Needless
> > to say, this was a painful experience.
>
> You have my sympathies.  I've had similar experiences.  There's a
> reason I do backups every week.  :-)
>
>
> > Apparently removing the link files on my backup actually removed the
> > system files and the link files on the backup, leaving nothing on
> > either drive. (which is exactly an anti-backup)
>
> Removing a symbolic link will have no effect on the target of said
> link.  Something else went wrong here.
>
>
> > Should I have booted from a CD disk, to safely scrub the files on the
> > backup drive, then copy from the hard drives to the backup?  Both file
> > systems would be off line, so it would appear that this might be the
> > way to go.
>
> That shouldn't be necessary, if you've got things set up
> correctly.  You need to do that sort of thing for disaster
> recovery, but not for regular backups.
>
>
> > Should I be using something different than the "cp -ruvp" and "rsync
> > -av" commands to do backups?
>
> Maybe try "cp --archive", to make sure that all the file
> ownerships and permissions are saved.  That said, I would
> recommend using dedicated backup software, such as Dirvish
> (<http://www.dirvish.org/>), to do your backups.  There is a
> package for Ubuntu, I believe.
>
> Dirvish runs from the command line, and uses rsync to copy the
> files.  The advantage of Dirvish is that it uses hard links to
> essentially "fake" a full backup every time it's run.  Rsync
> copies only those files that have changed since the prior backup,
> and builds hard links to the rest.  This saves time and space --
> especially space.  The downside to Dirvish is that it's not the
> simplest software to set up.  You have to read the man pages very
> thoroughly.  There are articles on Keith L.'s Dirvish website that
> are very helpful.  There is also a Dirvish mailing list that can
> be quite helpful.  I run Dirvish myself, to make weekly backups of
> all two of my systems.  Call me a very satisfied customer.
>
>
> > Finally, I won't mind if you say that this was not one of my
> > brightest moves.
>
> Heh.  I know how you feel, trust me.  I've been there.
>
> Anyway, I hope this helps.
>
> --Dale
>
> --
> The Dilettante's Version of the Three Laws of Thermodynamics:
> One:  You Can't Win.
> Two:  You Can't Even Break Even.
> Three:  You Cannot Get Out of the Game.
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-- 
p.j.timlick at ieee.org
www.timlick.com
503-476-3119
10990 NE Paren Springs Rd.
Dundee OR 97115



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