5.4. Backing up ext2/3/4 File Systems

Procedure 5.1. An Example of ext2/3/4 File System Backup

  1. All data must be backed up before attempting any kind of restore operation. Data backups should be made on a regular basis. In addition to data, there is configuration information that should be saved, including /etc/fstab and the output of fdisk -l. Running an sosreport/sysreport will capture this information and is strongly recommended.
    # cat /etc/fstab
    LABEL=/            /               ext3    defaults        1 1
    LABEL=/boot1       /boot           ext3    defaults        1 2
    LABEL=/data        /data           ext3    defaults        0 0
    tmpfs              /dev/shm        tmpfs   defaults        0 0
    devpts             /dev/pts        devpts  gid=5,mode=620  0 0
    sysfs              /sys            sysfs   defaults        0 0
    proc               /proc           proc    defaults        0 0
    LABEL=SWAP-sda5    swap            swap    defaults        0 0
    /dev/sda6          /backup-files   ext3    defaults        0 0
    
    # fdisk -l
       Device Boot    Start      End    Blocks      Id  System
    /dev/sda1 *           1       13    104391      83  Linux
    /dev/sda2            14      1925   15358140    83  Linux
    /dev/sda3          1926      3200   10241437+   83  Linux
    /dev/sda4          3201      4864   13366080    5   Extended
    /dev/sda5          3201      3391   1534176     82  Linux swap / Solaris
    /dev/sda6          3392      4864   11831841    83  Linux
    
    In this example, we will use the /dev/sda6 partition to save backup files, and we assume that /dev/sda6 is mounted on /backup-files.
  2. If the partition being backed up is an operating system partition, bootup your system into Single User Mode. This step is not necessary for normal data partitions.
  3. Use dump to back up the contents of the partitions:
    # dump -0uf /backup-files/sda1.dump /dev/sda1
    # dump -0uf /backup-files/sda2.dump /dev/sda2
    # dump -0uf /backup-files/sda3.dump /dev/sda3

    Note

    If the system has been running for a long time, it is advisable to run e2fsck on the partitions before backup.

    Important

    When backing up operating system partitions, the partition must be unmounted.
    While it is possible to back up an ordinary data partition while it is mounted, it is advisable to unmount it where possible. The results of attempting to back up a mounted data partition can be unpredictable.
    If you need to back up a mounted file system using dump, do so when the file system is not under a heavy load. The more activity is happening on the file system when backing up, the higher the risk of backup corruption is.
    If you want to do a remote backup, you can use both ssh or configure a non-password login:
    # dump -0u -f - /dev/sda1 | ssh root@remoteserver.example.com dd of=/tmp/sda1.dump

    Note

    If using standard redirection, the -f option must be passed separately.