Backing up the OS - Re: Rebuilding a failing drive

Robert Moskowitz <rgm@xxxxxxxxxxxxxxx> · Mon, 21 Nov 2016 15:16:15 -0500



    On 11/21/2016 01:42 PM, George N. White
      III wrote:

    
      On Mon, Nov 21, 2016 at 12:59 PM, Robert Moskowitz
        <rgm@xxxxxxxxxxxxxxx>
        wrote:

        
                On 11/21/2016 09:20 AM, Matthew Miller wrote:

                
                  On Mon, Nov 21, 2016 at 08:21:01AM -0500, Robert
                  Moskowitz wrote:

                  
                    I have a 1TB drive that is getting I/O  errors
                    enough that while I

                    What is a good way to move the OS and all the data? 
                    I used

                    Clonezilla some many years ago, but that does not
                    seem to be the way

                    to go when there are bad sections on the source
                    drive?

                  
                  Not helpful _now_, but consider making sure you have
                  backups once you

                  start using the new system. Then, next time this
                  happens, forget

                  worrying about transferring from a failing drive and
                  just restore your

                  backup.

                
              The data is backed up.  In fact it was one of the rsync
              cron tasks that wedged the system while I was gone.  The
              I/O did not seem to be in the data, but perhaps some temp
              or other storage needed.

            
            Backups should periodically read the entire disk, so
              may encounter bad sectors in areas that are not often read
              in normal operation.  Backups that take 

            
            too long to run are often the first indication of a
              failing disk.

            
              The challenge is the OS and software configs.  Actually
              the system is a ClearOS file server and there are all
              those config information scattered around by ClearOS.  I
              back up the whole /var/flexshare, but there is a lot more
              to their setup and no 'clear' directions from them. 
              Building a new server from scratch would be painful. Last
              year (when I had time while building up my contract work)
              I looked into building my own Samba 4 server, but dropped
              it.  Anyway, I have yet to find directions on a good way
              to maintain a running backup of the OS for a straight
              rebuild.
            

            After many experiences with having to reinstall the OS
              in order to install the backup client needed to restore
              user data, I make it a practice to keep a 

            
            base OS with current updates handy. 

            
    How does on 'backup the entire disk' and/or build a 'base OS with
    current updates'?  Can you point me to some guidance?

    
    thanks

    
              Without that I end up reinstalling the OS and then
              doing multiple updates.   If you do a few updates a week
              and

            
            hit a problem then it usually isn't hard to figure out
              which package caused the issue, but on a system that has
              been in service for a few years with 100's updates,
              getting form a fresh install from the original media back
              to an up-to-date running system may not be easy.   With
              systems that don't have restrictive licenses, you can just
              dd the base system to a fresh disk, change the system name
              and add the user(s), then install the backup client,
              restore the user data, and reinstall end-user
              applications.   

              
            ddrescue often recovers nearly all the files, so even
              if the resulting image isn't fully working you may be able
              to recover most of the configuration data.

            
                  If this is a desktop system with room for it, consider
                  buying *two*

                  drives and mirroring them. That's not a backup (since
                  errors and

                  mistakes get propagated instantly, and because it's in
                  the same

                  physical location), but makes situations like this
                  rare (at least, if

                  you replace as soon as you start seeing errors instead
                  of waiting for a

                  double failure).

                  
              I could never figure out what mirroring failing sectors
              meant.

            
            Not sure of the context, but the first sign of a
              failing disk is often a massive decrease in 

            
            performance which I'm told is due to multiple re-reads
              of a sector.   When a sector shows

              signs of failing, disk firmware copies the data to a spare
              sector.  If the new disk doesn't 

            
            arrive quickly you then see disk failure with a code
              that translates to "no spare sectors left 

            
            on device".

            
          George N. White III <aa056@xxxxxxxxxxxxxx>

            Head of St. Margarets Bay, Nova Scotia
        
      
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