Backing up ext3 root partition with dd

["Yassin Hania-CHY002" <Hania Yassin motorola com>]

Title: Message

Is there a reason why an ext3 root partition cannot be copied to an alternate partition using the "dd" command?  

The dd is copying the mounted root partition into an alternate partition that is not mounted.  The dd returns success, but the fsck on that partition fails with errors as follows:

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fsck 1.37 (21-Mar-2005)
/dev/Active_Update/root2: recovering journal
/dev/Active_Update/root2: Clearing orphaned inode 57554 (uid=0, gid=0, mode=010600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57552 (uid=1010, gid=3002, mode=010600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57548 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57547 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57546 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57545 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57544 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57543 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57542 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57541 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57540 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57539 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57538 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57537 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Clearing orphaned inode 57536 (uid=0, gid=0, mode=020600, size=0)
/dev/Active_Update/root2: Deleted inode 90369 has zero dtime.  FIXED.
/dev/Active_Update/root2: Inode 90370 is in use, but has dtime set.  FIXED.
/dev/Active_Update/root2: Inode 90371 is in use, but has dtime set.  FIXED.
/dev/Active_Update/root2: Inode 90372 is in use, but has dtime set.  FIXED.
/dev/Active_Update/root2: Inode 90373 is in use, but has dtime set.  FIXED.
/dev/Active_Update/root2: Inode 90373 has imagic flag set.  retfrom fsck is 1024

-------------------------------

 

When mounting that partition, an error is logged to /var/log/messages as follows:

EXT3-fs warning: mounting fs with errors, running e2fsck is recommended

 

We are seeing this on boxes running RHEL4 and even boxes running a PPC version of Linux.

This failure is not seen on every run of the scripts, and is mostly seen when mirroring the root partition.

 

Here is the script which reproduces this ext3 corruption after running it 5-6 times:

------------------------------------------

#!/usr/bin/perl -w
my $ret;

##
## Determine the backup partitions
##
my @temp =  `cat /etc/fstab | grep alt_root`;
my (@temp2, @alt_parts, @parts, @part);
my $cnt = 0;
foreach (@temp)
{
   @temp2 = split / /;
   push @alt_parts, $temp2[0];
}

##
## Determine the active partitions
##
@temp = `cat /etc/fstab | grep Active_Update | grep -v alt_root | grep -v log | grep -v swap`;
foreach (@temp)
{
   @temp2 = split / /;
   push @parts, $temp2[0];
}


while (`cat /var/log/messages | grep -ci "running e2fsck is recommended"` <= 0)
{
   foreach my $alt_part (@alt_parts)
   {
      $alt_part =~ /(\D+)\d/;
      @part = grep /$1/, @parts;
      `dd if=$part[0] of=$alt_part > /dev/null 2>&1`;
      $ret = $?;

      ##
      ## Abort if the partition copy fails as there is likely something
      ## seriously wrong
      ##
      if ($ret != 0)
      {
         `logger "ERROR: Problems copying data to $alt_part."`;
         `logger "       Contact Motorola for assistance."`;
         `logger "Partition Copy exit code: $ret"`;
         exit 1;
      }

      ##
      ## Check the filesystem on the copied partition
      ##
      `/sbin/fsck -fp $alt_part > /dev/null 2>&1`;
      $ret = $?;
      `logger "fsck exit code for $alt_part was: $ret"`;
   }

   ##
   ## Modify the copied partition
   ##
   `mount /mnt/alt_root; rm -f /mnt/alt_root/bob; touch /mnt/alt_root/bob; umount /mnt/alt_root`;
}

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