[PLUG] need help with backups/restores and grub

Word Wizard Word.Wizard at comcast.net
Thu Apr 16 19:15:19 UTC 2009


Another path to the goal 

I did some more research about the  'dd' command (yes I am a newbie) and
that tool doesn't have tar's weakness in this area. Copying the entire
partition takes up ten times more space than just tar-ing the
individuals files but it is faster than my preferred bzip2 compression
format.  Once I starting studying disk partitions I realized that it was
better to install the / file system on one partition and  /home on a
separate partition. That way I could dd my / partition and tar my /home.
The default Ubuntu installation model places  / and /home on the same
partition so it took me some time and research to realize that manually
designating separate partitions for different parts of the file system
was more useful. 

Before using dd on /, I boot up with and run in the installation DVD
Gnome environment. That way I can access / as a dismounted partition
without worrying about file changes during a backup. 

When done,  I mount my /home partition as /media/disk-1 and tar that
one.The datablock location  problem you pointed out does not seem to be
an issue with my /home partition. As it isn't the active /home partition
for that live/installation environment, I assume there will be
minimal/no file changes while it's being tar-ed. Just to be sure I
created one dd /home partition backup to use in case I've missed
something. I'm sure I have and I trust someone will point it out.

With Windows I never needed to know anything about partitioning after
the installation partition selection choice. With Linux it appears I
won't get very far without an in-depth knowledge of disk geography and
the Linux tools used to work with storage media. The upside is that once
I learn the tools I can do things in different ways specific to a given
need. I prefer having more tools even though it can be frustrating to
want to do something I know other Linux users can do but I can't do
because I haven't learned enough about the process.  


Thanks again for the help & information. Linux is becoming more fun and
less a pain as I learn more.  


Word Wizard 

On Wed, 2009-04-15 at 19:59 -0700, Dwight Hubbard wrote:

> Grub stores the actual physical locations of the datablocks of it's
> stage 1.5 or stage 2 files in the bootblock.  If you restore from a
> tar archive the location of the blocks for the grub stage files will
> almost certainly be different and as a result grub will generate an
> error 15 because it can't find them.  
> 
> After restoring from a tar archive you need to chroot into the newly
> restored filesystem and run a grub-install to cause the restored
> system to write the grub stage file locations to the boot block.
> 
> Or you can restore grub from the grub command.  If my memory serves
> the commands would look something like this (assuming your /boot
> filesystem (hd0,1) and you want the boot block on the first hard disk:
> root (hd0,1)
> setup (hd0)
> 
> 
> On Thu, Apr 9, 2009 at 6:13 PM, Word Wizard <Word.Wizard at comcast.net>
> wrote:
> 
>         
>         One of the reasons I adopted Linux (Ubuntu Intrepid) was that,
>         unlike
>         Windows,  it SUPPOSEDLY allowed one to fully back up the
>         entire system,
>         system files and all, and restore them. So if you installed
>         files or
>         configured your system and made mistakes, you revert to a
>         previous
>         system. That's the theory. The reality is  a bitter
>         disappointment.
>         
>         I sudo su, change to /  directory and use the following
>          command and
>         generate a valid tar backup:
>         
>         tar cvpjf /home/username/BackUp/Archives/total_backup.tar.bz2
>         --exclude="/home//username/HD_1"
>         --exclude="/home//username/HD_2"
>         --exclude="/home//username/.thumbnails"
>         --exclude="/home//username/.mozilla/default/Cache"
>         --exclude="/proc"
>         --exclude="/lost+found" --exclude="/media" --exclude="/mnt"
>         --exclude="/sys" /
>         
>         To restore,  I sudo su, change to the / directory and use the
>         following
>          command:
>         
>         tar xvpjf /home/username/BackUp/Archives/total_backup.tar.bz2
>          -C /
>         
>         First problem. Upon reboot I get an "error 15" Can't find the
>         grub
>         files. They are there but It seems the problem may be with
>          using UUIDs
>         instead of (hd0) notation. The UUIDs change. What no-life
>         propeller head
>         chose to use UUIDs anyway?
>         
>         It gets worse. I tried  booting from the distro DVD
>         (Intrepid)  and
>         using grub to 'find /boot/grub/stage1'.
>         
>         grub finds it (hd0,5). That's the correct location. I use the
>         sudo su,
>         then the root (hd0,5) command. No error messages. I use the
>          setup (hd0)
>         command and the output says it found the  /boot/grub/stage1
>         file and is
>         writing (hd0)/boot/grub/menu/.lst.
>         
>         BUT... It does not write (hd0)/boot/grub/menu/.lst. Anywhere.
>         I check
>         the root drive and the old /boot/grub/menu/.lst is still
>         there. Even if
>         I rename it, no new menu.lst appears .
>         
>         
>         What am I doing wrong? Or is Linux still not ready for prime
>         time and
>         only for hackers?
>         
>         
>         
>         
>         
>         _______________________________________________
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> 
> 
> 
> 
> -- 
> Dwight Hubbard
> Owner Effective Automation Solutions
> Website: http://effectiveautomationsolutions.com
> Blog: http://computing.dwighthubbard.info
> Email: dwight at dwighthubbard.com
> Phone: (503) 616-4493
> Redhat Certified Engineer - RHCE #804007137224095
> VMware Certified Professional - VCP #18529



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