dump 和 restore 命令

概述

dump 命令会检查文件系统中的文件，确定需要备份的文件，并将这些文件复制到指定的磁盘、磁带或其他存储介质。restore 命令执行与 dump 相反的功能。

此实用程序适用于以下文件系统

• ext2
• ext3
• ext4

技巧

对于 xfs 文件系统，请使用 xfsdump。

此处是项目的首页。

在使用此实用程序之前，请运行以下命令进行安装

Shell > dnf -y install dump

安装完成后，可以使用两个常用的命令行工具

• dump
• restore

dump 命令

此命令主要有两个用途

• 执行备份 (dump) 操作 - dump [选项] -f <文件名> <文件1> ...
• 查看备份 (dump) 信息 - dump [-W | -w]

常用选项包括

• -<level> - 备份级别。使用时，请将“level”替换为 0-9 之间的任意数字。数字 0 代表完全备份，而其他数字代表增量备份。
• -f <文件名> - 指定备份后的文件名和路径。
• -u - 成功备份后，将备份时间记录在 /etc/dumpdates 文件中。当被备份对象是独立分区时，您可以使用 -u 选项。但是，当备份对象是未分区目录时，您不能使用 -u 选项。
• -v - 在备份过程中显示处理详情。
• -W - 用于查看 dump 信息的选项。
• -z[LEVEL] - 使用 zlib 库调整压缩级别，默认压缩级别为 2。例如，您可以将备份文件压缩为 .gz 格式。压缩级别的可调范围是 1-9。
• -j[LEVEL] - 使用 bzlib 库调整压缩级别，默认压缩级别为 2。例如，您可以将备份文件压缩为 .bz2 格式。压缩级别的可调范围是 1-9。

dump 使用示例

1. 对根分区执行完全备份

   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. 成功 dump 后，检查相关信息

   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. 在完全备份的基础上实施增量备份

   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. 对于未分区目录，您只能使用完全备份 (-0) 选项，而不能使用 -u 选项

   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
   

对 /etc/ 目录执行增量备份将导致错误

```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 命令

此命令的用法是 - restore <模式(标志)> [选项] -f <dump文件>

模式 (标志) 可以是以下之一

• -C - 比较模式。Restore 会读取备份并将其内容与磁盘上的文件进行比较。它主要用于在分区备份后进行比较。在此模式下，restore 只根据原始数据进行比较。如果磁盘上有新数据，您无法比较或检测到。
• -i - 交互模式。此模式允许从 dump 中交互式恢复文件。
• -t - 列表模式。列出备份文件中包含的数据。
• -r - 恢复 (重建) 模式。如果采用“完全备份 + 增量备份”的方式，恢复数据将按时间顺序进行。
• -x - 提取模式。从备份文件中提取部分或全部文件。

restore 使用示例

1. 从 /tmp/etc-full-20241208.bak.bz2 恢复数据

   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
   

   您会注意到，成功恢复后会出现一个名为 restoresymtable 的文件。此文件很重要，它用于增量备份系统的恢复操作。

2. 在交互模式下处理备份文件

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

   您可以输入 ? 来查看此模式下可用的交互命令。

作者：李天赐

贡献者：Steven Spencer