5.打包与压缩

本章同步视频：https://edu.51cto.com/sd/e4874

5.3 xfs文件系统的备份和恢复

       XFS提供了 xfsdump 和 xfsrestore 工具协助备份XFS文件系统中的数据。XFS不需要在备份前被卸载；对使用中的XFS文件系统做备份就可以保证镜像的一致性。XFS的备份和恢复的过程是可以被中断然后继续的，无须冻结文件系统。xfsdump 甚至提供了高性能的多线程备份操作——它把一次dump拆分成多个数据流，每个数据流可以被发往不同的目的地。

5.3.1 备份策略

1.完全备份

       完全备份是指把所有需要备份的数据全部备份。完全备份可以备份整块硬盘、整个分区或某个具体的目录。

       完全备份的好处是，所有数据都进行了备份，系统中任何数据丢失都能恢复，且恢复效率较高。

       完全备份的缺点也很明显，那就是需要备份的数据量较大，备份时间较长，备份了很多无用数据，占用的空间较大，所以完全备份不可能每天执行。

2.增量备份

       累计增量备份是指先进行一次完全备份，服务器运行一段时间之后，比较当前系统和完全备份的备份数据之间的差异，只备份有差异的数据。服务器继续运行，再经过一段时间，进行第二次增量备份。在进行第二次增量备份时，当前系统和第一次增量备份的数据进行比较，也是只备份有差异的数据。第三次增量备份是和第二次增量备份的数据进行比较，以此类推。

       采用累计增量备份的好处是，每次备份需要备份的数据较少，耗时较短，占用的空间较小；坏处是数据恢复比较麻烦，那么当进行数据恢复时，就要先恢复完全备份的数据，再依次恢复第一次增量备份的数据、第二次增量备份的数据和第三次增量备份的数据，最终才能恢复所有的数据。

3.差异备份

       差异备份也要先进行一次完全备份，但是和累计增量备份不同的是，每次差异备份都备份和原始的完全备份不同的数据。也就是说，差异备份每次备份的参照物都是原始的完全备份，而不是上一次的差异备份。

       相比较而言，差异备份既不像完全备份一样把所有数据都进行备份，也不像增量备份在进行数据恢复时那么麻烦，只要先恢复完全备份的数据，再恢复差异备份的数据即可。不过，随着时间的增加，和完全备份相比，变动的数据越来越多，那么差异备份也可能会变得数据量庞大、备份速度缓慢、占用空间较大。

5.3.2  XFS 文件系统备份xfsdump

1.xfsdump的限制

u  xfsdump不支援没有挂载的文件系统备份！所以只能备份已挂载的！

u  xfsdump必须使用 root 的权限才能操作 (涉及文件系统的关系)

u  xfsdump只能备份 XFS 文件系统啊！

u  xfsdump备份下来的数据 (档案或储存媒体) 只能让xfsrestore解析

u  xfsdump是透过文件系统的 UUID 来分辨各个备份档的，因此不能备份两个具有相同 UUID 的文件系统喔！

2.xfsdump - XFS filesystem incremental dump utility

[root@study ~]# xfsdump [-L S_label] [-M M_label] [-l #] [-f 备份档] 待备份资料

[root@study ~]# xfsdump -I

选项与参数：

-L  ：xfsdump会纪录每次备份的 session 标头，这里可以填写针对此文件系统的简易说明

-M  ：xfsdump可以纪录储存媒体的标头，这里可以填写此媒体的简易说明

-l  ：是 L 的小写，就是指定等级～有 0~9 共 10 个等级喔！ (预设为 0，即完整备份)

-f  ：有点类似 tar 啦！后面接产生的档案，亦可接例如 /dev/st0 装置文件名或其他一般档案档名等

-I  ：从 /var/lib/xfsdump/inventory 列出目前备份的信息状态

3.备份前准备

使用fdisk划分一个分区sda3，并格式化为xfs。（此部分操作省略）

[root@localhost mnt]# mount /dev/sda3 /mnt/sda3/    #挂载

[root@localhost mnt]# df -h /dev/sda3     #查看挂载情况，可省略

Filesystem      Size  Used Avail Use% Mounted on

/dev/sda3       197M   11M  187M   6% /mnt/sda3

[root@localhost mnt]# blkid /dev/sda3   #查看分区信息，可省略

/dev/sda3: UUID="f598c75c-bd26-4543-af2f-8192841c4c8b" TYPE="xfs"

4.完全备份

[root@localhost mnt]# touch /mnt/sda3/1.txt

[root@localhost mnt]# xfsdump -l 0 -f /tmp/sda3 /dev/sda3

xfsdump: using file dump (drive_simple) strategy

xfsdump: version 3.1.3 (dump format 3.0) - type ^C for status and control

 =============== dump label dialog =================

please enter label for this dump session (timeout in 300 sec)

 -> dump_sda3_20200331    #备份说明

session label entered: "dump_sda3_20200331"

 --------------------------------- end dialog ---------------------------------

xfsdump: level 0 dump of localhost.localdomain:/mnt/sda3

xfsdump: dump date: Tue Mar 31 20:30:53 2020

xfsdump: session id: 0dab0e83-90fb-4fef-88db-974bd0e5a2f3

xfsdump: session label: "dump_sda3_20200331"

xfsdump: ino map phase 1: constructing initial dump list

xfsdump: ino map phase 2: skipping (no pruning necessary)

xfsdump: ino map phase 3: skipping (only one dump stream)

xfsdump: ino map construction complete

xfsdump: estimated dump size: 21120 bytes

xfsdump: /var/lib/xfsdump/inventory created

 =============== media label dialog =================

please enter label for media in drive 0 (timeout in 300 sec)

 -> sda3      #备份媒体说明

media label entered: "sda3"

 --------------------------------- end dialog ---------------------------------

xfsdump: creating dump session media file 0 (media 0, file 0)

xfsdump: dumping ino map

xfsdump: dumping directories

xfsdump: dumping non-directory files

xfsdump: ending media file

xfsdump: media file size 21656 bytes

xfsdump: dump size (non-dir files) : 0 bytes

xfsdump: dump complete: 33 seconds elapsed

xfsdump: Dump Summary:

xfsdump:   stream 0 /tmp/sda3 OK (success)

xfsdump: Dump Status: SUCCESS

[root@localhost mnt]# ls /tmp/

root  sda3  test

#上面的备份命令需要交互，下面的命令无交互，常用于脚本。

[root@localhost mnt]# xfsdump -l 0 -L dump_sda3_20200331  -M sda3 -f /tmp/sda3 /dev/sda3

[root@localhost mnt]# xfsdump -I     #

file system 0:

fs id:  f598c75c-bd26-4543-af2f-8192841c4c8b

session 0:

mount point: localhost.localdomain:/mnt/sda3

device:  localhost.localdomain:/dev/sda3

time:  Tue Mar 31 20:42:51 2020

session label: "dump_sda3_20200331"

session id: b2315293-f79f-43b2-9276-157268eea187

level:  0

resumed: NO

subtree: NO

streams: 1

stream 0:

pathname: /tmp/sda3

start:  ino 131 offset 0

end:  ino 132 offset 0

interrupted: NO

media files: 1

media file 0:

mfile index: 0

mfile type: data

mfile size: 21656

mfile start: ino 131 offset 0

mfile end: ino 132 offset 0

media label: "sda3"

media id: 23a27bd0-e47b-4bee-9005-d530e6303f63

xfsdump: Dump Status: SUCCESS

5.第一次增量备份

[root@localhost mnt]# ls sda3/

1.txt

[root@localhost mnt]# touch sda3/2.txt

[root@localhost mnt]# ls sda3/

1.txt  2.txt

[root@localhost mnt]# xfsdump -l 1 -L dump_sda3_20200331-1 -M sda3 -f /tmp/sda3-1 /dev/sda3

xfsdump: using file dump (drive_simple) strategy

xfsdump: version 3.1.3 (dump format 3.0) - type ^C for status and control

xfsdump: level 1 incremental dump of localhost.localdomain:/mnt/sda3 based on level 0 dump begun Tue Mar 31 20:42:51 2020

xfsdump: dump date: Tue Mar 31 20:47:58 2020

xfsdump: session id: 989e4ade-b8c3-40be-9714-10c648f6b46c

xfsdump: session label: "dump_sda3_20200331-1"

xfsdump: ino map phase 1: constructing initial dump list

xfsdump: ino map phase 2: skipping (no pruning necessary)

xfsdump: ino map phase 3: skipping (only one dump stream)

xfsdump: ino map construction complete

xfsdump: estimated dump size: 21120 bytes

xfsdump: creating dump session media file 0 (media 0, file 0)

xfsdump: dumping ino map

xfsdump: dumping directories

xfsdump: dumping non-directory files

xfsdump: ending media file

xfsdump: media file size 21680 bytes

xfsdump: dump size (non-dir files) : 0 bytes

xfsdump: dump complete: 0 seconds elapsed

xfsdump: Dump Summary:

xfsdump:   stream 0 /tmp/sda3-1 OK (success)

xfsdump: Dump Status: SUCCESS

[root@localhost mnt]# xfsdump -I

file system 0:

fs id:  f598c75c-bd26-4543-af2f-8192841c4c8b

session 0:

mount point: localhost.localdomain:/mnt/sda3

device:  localhost.localdomain:/dev/sda3

time:  Tue Mar 31 20:42:51 2020

session label: "dump_sda3_20200331"

session id: b2315293-f79f-43b2-9276-157268eea187

level:  0

resumed: NO

subtree: NO

streams: 1

stream 0:

pathname: /tmp/sda3

start:  ino 131 offset 0

end:  ino 132 offset 0

interrupted: NO

media files: 1

media file 0:

mfile index: 0

mfile type: data

mfile size: 21656

mfile start: ino 131 offset 0

mfile end: ino 132 offset 0

media label: "sda3"

media id: 23a27bd0-e47b-4bee-9005-d530e6303f63

session 1:

mount point: localhost.localdomain:/mnt/sda3

device:  localhost.localdomain:/dev/sda3

time:  Tue Mar 31 20:47:58 2020

session label: "dump_sda3_20200331-1"

session id: 989e4ade-b8c3-40be-9714-10c648f6b46c

level:  1

resumed: NO

subtree: NO

streams: 1

stream 0:

pathname: /tmp/sda3-1

start:  ino 132 offset 0

end:  ino 133 offset 0

interrupted: NO

media files: 1

media file 0:

mfile index: 0

mfile type: data

mfile size: 21680

mfile start: ino 132 offset 0

mfile end: ino 133 offset 0

media label: "sda3"

media id: 42121b62-abf0-4e26-98f1-48d50f01b633

xfsdump: Dump Status: SUCCESS

6.第二次增量备份

[root@localhost mnt]# touch sda3/{3,4,5,6}.txt

[root@localhost mnt]# ls sda3/

1.txt  2.txt  3.txt  4.txt  5.txt  6.txt

[root@localhost mnt]# xfsdump -l 2 -L dump_sda3_20200331-2 -M sda3 -f /tmp/sda3-2 /dev/sda3

xfsdump: using file dump (drive_simple) strategy

xfsdump: version 3.1.3 (dump format 3.0) - type ^C for status and control

xfsdump: level 2 incremental dump of localhost.localdomain:/mnt/sda3 based on level 1 dump begun Tue Mar 31 20:47:58 2020

xfsdump: dump date: Tue Mar 31 20:56:34 2020

xfsdump: session id: 1a6e946b-fd0e-4e70-bb00-b82c04291de7

xfsdump: session label: "dump_sda3_20200331-2"

xfsdump: ino map phase 1: constructing initial dump list

xfsdump: ino map phase 2: skipping (no pruning necessary)

xfsdump: ino map phase 3: skipping (only one dump stream)

xfsdump: ino map construction complete

xfsdump: estimated dump size: 22080 bytes

xfsdump: creating dump session media file 0 (media 0, file 0)

xfsdump: dumping ino map

xfsdump: dumping directories

xfsdump: dumping non-directory files

xfsdump: ending media file

xfsdump: media file size 23624 bytes

xfsdump: dump size (non-dir files) : 0 bytes

xfsdump: dump complete: 0 seconds elapsed

xfsdump: Dump Summary:

xfsdump:   stream 0 /tmp/sda3-2 OK (success)

xfsdump: Dump Status: SUCCESS

[root@localhost mnt]# xfsdump -I

file system 0:

fs id:  f598c75c-bd26-4543-af2f-8192841c4c8b

session 0:

mount point: localhost.localdomain:/mnt/sda3

device:  localhost.localdomain:/dev/sda3

time:  Tue Mar 31 20:42:51 2020

session label: "dump_sda3_20200331"

session id: b2315293-f79f-43b2-9276-157268eea187

level:  0

resumed: NO

subtree: NO

streams: 1

stream 0:

pathname: /tmp/sda3

start:  ino 131 offset 0

end:  ino 132 offset 0

interrupted: NO

media files: 1

media file 0:

mfile index: 0

mfile type: data

mfile size: 21656

mfile start: ino 131 offset 0

mfile end: ino 132 offset 0

media label: "sda3"

media id: 23a27bd0-e47b-4bee-9005-d530e6303f63

session 1:

mount point: localhost.localdomain:/mnt/sda3

device:  localhost.localdomain:/dev/sda3

time:  Tue Mar 31 20:47:58 2020

session label: "dump_sda3_20200331-1"

session id: 989e4ade-b8c3-40be-9714-10c648f6b46c

level:  1

resumed: NO

subtree: NO

streams: 1

stream 0:

pathname: /tmp/sda3-1

start:  ino 132 offset 0

end:  ino 133 offset 0

interrupted: NO

media files: 1

media file 0:

mfile index: 0

mfile type: data

mfile size: 21680

mfile start: ino 132 offset 0

mfile end: ino 133 offset 0

media label: "sda3"

media id: 42121b62-abf0-4e26-98f1-48d50f01b633

session 2:

mount point: localhost.localdomain:/mnt/sda3

device:  localhost.localdomain:/dev/sda3

time:  Tue Mar 31 20:56:34 2020

session label: "dump_sda3_20200331-2"

session id: 1a6e946b-fd0e-4e70-bb00-b82c04291de7

level:  2

resumed: NO

subtree: NO

streams: 1

stream 0:

pathname: /tmp/sda3-2

start:  ino 133 offset 0

end:  ino 137 offset 0

interrupted: NO

media files: 1

media file 0:

mfile index: 0

mfile type: data

mfile size: 23624

mfile start: ino 133 offset 0

mfile end: ino 137 offset 0

media label: "sda3"

media id: f410ea13-eada-4566-87c8-844b1a939ce1

xfsdump: Dump Status: SUCCESS