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dump and restore command

Overview

dump examines files in a filesystem, determines which to back up, and copies those files to a specified disk, tape, or other storage medium. The restore command performs the inverse function of dump.

This utility applies to the following file systems:

  • ext2
  • ext3
  • ext4

Tip

For the xfs file system, use xfsdump.

This is the project's homepage.

Before using this utility, run the following command to install it:

Shell > dnf -y install dump

After installation, two commonly used command tools are available:

  • dump
  • restore

dump command

There are two main uses for this command:

  • Perform backup (dump) operations - dump [option(s)] -f <File-Name> <File1> ...
  • Review backup (dump) information - dump [-W | -w]

Common options are:

  • -<level> - Backup level. Please replace "level" with any number from 0-9 when used. The number 0 represents full backup, while other numbers represent incremental backup.
  • -f <File-Name> - Specify the file name and path after backup.
  • -u - After a successful backup, record the backup time in the /etc/dumpdates file. You can use the -u option when the backed-up object is an independent partition. However, you cannot use the -u option when the backup object is a non-partitioned directory.
  • -v - Display the processing details during the backup process.
  • -W - An option for viewing dump information.
  • -z[LEVEL] - Adjust the compression level using the zlib library, with a default compression level of 2. For example, you can compress the backup file to .gz format. The adjustable range of compression level is 1-9.
  • -j[LEVEL] - Adjust the compression level using the bzlib library, with a default compression level of 2. For example, you can compress the backup file to .bz2 format. The adjustable range of compression level is 1-9.

Example of using dump

  1. Perform a Full Backup of the root partition:

    Shell > dump -0u -j3 -f /tmp/root-20241208.bak.bz2 /
DUMP: Date of this level 0 dump: Sun Dec  8 19:04:39 2024
DUMP: Dumping /dev/nvme0n1p2 (/) to /tmp/root-20241208.bak.bz2
DUMP: Label: none
DUMP: Writing 10 Kilobyte records
DUMP: Compressing output at transformation level 3 (bzlib)
DUMP: mapping (Pass I) [regular files]
DUMP: mapping (Pass II) [directories]
DUMP: estimated 14693111 blocks.
DUMP: Volume 1 started with block 1 at: Sun Dec  8 19:04:41 2024
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
DUMP: 20.69% done at 10133 kB/s, finished in 0:19
DUMP: 43.74% done at 10712 kB/s, finished in 0:12
DUMP: 70.91% done at 11575 kB/s, finished in 0:06
DUMP: 93.23% done at 11415 kB/s, finished in 0:01
DUMP: Closing /tmp/root-20241208.bak.bz2
DUMP: Volume 1 completed at: Sun Dec  8 19:26:08 2024
DUMP: Volume 1 took 0:21:27
DUMP: Volume 1 transfer rate: 5133 kB/s
DUMP: Volume 1 14722930kB uncompressed, 6607183kB compressed, 2.229:1
DUMP: 14722930 blocks (14377.86MB) on 1 volume(s)
DUMP: finished in 1287 seconds, throughput 11439 kBytes/sec
DUMP: Date of this level 0 dump: Sun Dec  8 19:04:39 2024
DUMP: Date this dump completed:  Sun Dec  8 19:26:08 2024
DUMP: Average transfer rate: 5133 kB/s
DUMP: Wrote 14722930kB uncompressed, 6607183kB compressed, 2.229:1
DUMP: DUMP IS DONE

Shell > ls -lh /tmp/root-20241208.bak.bz2
-rw-r--r-- 1 root root 6.4G Dec  8 19:26 /tmp/root-20241208.bak.bz2

  2. After successful dumping, check the relevant information:

    Shell > cat /etc/dumpdates
/dev/nvme0n1p2 0 Sun Dec  8 19:04:39 2024 +0800

Shell > dump -W
Last dump(s) done (Dump '>' file systems):
/dev/nvme0n1p2        (     /) Last dump: Level 0, Date Sun Dec  8 19:04:39 2024

  3. Implement Incremental Backup on the basis of Full Backup:

    Shell > echo "jack" >> /tmp/tmpfile.txt

Shell > dump -1u -j4 -f /tmp/root-20241208-LV1.bak.bz2 /
DUMP: Date of this level 1 dump: Sun Dec  8 19:38:51 2024
DUMP: Date of last level 0 dump: Sun Dec  8 19:04:39 2024
DUMP: Dumping /dev/nvme0n1p2 (/) to /tmp/root-20241208-LV1.bak.bz2
DUMP: Label: none
DUMP: Writing 10 Kilobyte records
DUMP: Compressing output at transformation level 4 (bzlib)
DUMP: mapping (Pass I) [regular files]
DUMP: mapping (Pass II) [directories]
DUMP: estimated 6620898 blocks.
DUMP: Volume 1 started with block 1 at: Sun Dec  8 19:38:58 2024
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
DUMP: 38.13% done at 8415 kB/s, finished in 0:08
DUMP: 75.30% done at 8309 kB/s, finished in 0:03
DUMP: Closing /tmp/root-20241208-LV1.bak.bz2
DUMP: Volume 1 completed at: Sun Dec  8 19:52:03 2024
DUMP: Volume 1 took 0:13:05
DUMP: Volume 1 transfer rate: 8408 kB/s
DUMP: Volume 1 6620910kB uncompressed, 6600592kB compressed, 1.004:1
DUMP: 6620910 blocks (6465.73MB) on 1 volume(s)
DUMP: finished in 785 seconds, throughput 8434 kBytes/sec
DUMP: Date of this level 1 dump: Sun Dec  8 19:38:51 2024
DUMP: Date this dump completed:  Sun Dec  8 19:52:03 2024
DUMP: Average transfer rate: 8408 kB/s
DUMP: Wrote 6620910kB uncompressed, 6600592kB compressed, 1.004:1
DUMP: DUMP IS DONE

Shell > cat /etc/dumpdates
/dev/nvme0n1p2 0 Sun Dec  8 19:04:39 2024 +0800
/dev/nvme0n1p2 1 Sun Dec  8 19:38:51 2024 +0800

Shell > dump -W
Last dump(s) done (Dump '>' file systems):
/dev/nvme0n1p2        (     /) Last dump: Level 1, Date Sun Dec  8 19:38:51 2024

  4. For non-partitioned directory, you can only use the Full Backup (-0) option, not the -u option:

    Shell > dump -0uj -f /tmp/etc-full-20241208.bak.bz2 /etc/
DUMP: You can't update the dumpdates file when dumping a subdirectory
DUMP: The ENTIRE dump is aborted.

Shell > dump -0j -f /tmp/etc-full-20241208.bak.bz2 /etc/
DUMP: Date of this level 0 dump: Sun Dec  8 20:00:38 2024
DUMP: Dumping /dev/nvme0n1p2 (/ (dir etc)) to /tmp/etc-full-20241208.bak.bz2
DUMP: Label: none
DUMP: Writing 10 Kilobyte records
DUMP: Compressing output at transformation level 2 (bzlib)
DUMP: mapping (Pass I) [regular files]
DUMP: mapping (Pass II) [directories]
DUMP: estimated 28204 blocks.
DUMP: Volume 1 started with block 1 at: Sun Dec  8 20:00:38 2024
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
DUMP: Closing /tmp/etc-full-20241208.bak.bz2
DUMP: Volume 1 completed at: Sun Dec  8 20:00:40 2024
DUMP: Volume 1 took 0:00:02
DUMP: Volume 1 transfer rate: 3751 kB/s
DUMP: Volume 1 29090kB uncompressed, 7503kB compressed, 3.878:1
DUMP: 29090 blocks (28.41MB) on 1 volume(s)
DUMP: finished in 2 seconds, throughput 14545 kBytes/sec
DUMP: Date of this level 0 dump: Sun Dec  8 20:00:38 2024
DUMP: Date this dump completed:  Sun Dec  8 20:00:40 2024
DUMP: Average transfer rate: 3751 kB/s
DUMP: Wrote 29090kB uncompressed, 7503kB compressed, 3.878:1
DUMP: DUMP IS DONE

Performing an incremental backup of the /etc/ directory will result in an error:

```bash
Shell > dump -1j -f /tmp/etc-incr-20241208.bak.bz2 /etc/
DUMP: Only level 0 dumps are allowed on a subdirectory
DUMP: The ENTIRE dump is aborted.
```

restore command

The usage of this command is - restore <mode(flag)> [option(s)] -f <Dump-File>

The mode (flag) can be one of the following:

  • -C - Comparison mode. Restore reads the backup and compares its contents with files on the disk. It is mainly used to compare after performing a backup on a partition. In this mode, restore only compares changes based on the original data. If there is new data on the disk, you cannot compare or detect it.
  • -i - Interactive mode. This mode allows interactive restoration of files from a dump.
  • -t - List mode. List what data is in the backup file.
  • -r - Restore (rebuild) mode. If it is a "Full Backup + Incremental Backup" method, restoring data will occur chronologically.
  • -x - Extraction mode. Extract some or all files from the backup file.

Example of using restore

  1. Restore data from /tmp/etc-full-20241208.bak.bz2 :

    Shell > mkdir /tmp/data/

Shell > restore -t -f /tmp/etc-full-20241208.bak.bz2

Shell > cd /tmp/data/ ; restore -r -f /tmp/etc-full-20241208.bak.bz2

Shell > ls -l /tmp/data/
total 4992
drwxr-xr-x. 90 root root    4096 Dec  8 17:13 etc
-rw-------   1 root root 5107632 Dec  8 20:39 restoresymtable

    As you can see, a file named restoresymtable shows up after a successful restore. This file is important. It is for incremental backup system restore operations.

  2. Process backup files in Interactive mode:

    Shell > restore -i -f /tmp/etc-full-20241208.bak.bz2
Dump tape is compressed.

restore > ?

    You can type ? to view the available interactive commands in this mode.

Author: tianci li

Contributors: Steven Spencer