1 目标
- 如果宿主机操作故障系统或其他原因，在其上已经挂载使用的相关LVM信息和数据能否恢复？
- 重开一台主机，挂载已构建LVM的硬盘组，能否保证原有数据的安全完整？
2 实验环境
2.1 宿主机
- 名称 lvm0
- 系统盘8G
- 操作系统 Debian 10
2.2 副主机
- 名称 lvm1
- 系统盘8G
- 操作系统 Ubuntu 20.04
2.3 存储硬盘
- 容量10 G
- 数据 3 块
3 过程
3.1 宿主机设置 LVM
设定 lvm
分区设置标签为 8e 即 lvm
root@lvm0:~# fdisk /dev/sdb
root@lvm0:~# fdisk /dev/sdc
root@lvm0:~# fdisk /dev/sdd
创建物理卷
root@lvm0:~# pvcreate /dev/sd[bdc]1
创建卷组
root@lvm0:~# vgcreate vg0 /dev/sd[bdc]1
创建逻辑卷
root@lvm0:~# lv --size 15G --name lv0 vg0
放入测试数据
root@lvm0:~# mnt /dev/vg0/lv0 /mnt
root@lvm0:~# git clone best.git
root@lvm0:~# ls /mnt
best lost+found
root@lvm0:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 478M 0 478M 0% /dev
tmpfs 99M 3.0M 96M 4% /run
/dev/sda1 6.9G 1.5G 5.1G 23% /
tmpfs 494M 0 494M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 494M 0 494M 0% /sys/fs/cgroup
tmpfs 99M 0 99M 0% /run/user/0
/dev/mapper/vg0-lv0 15G 168M 14G 2% /mnt
然后我们关闭宿主机，假定它已经挂掉！
root@lvm0:~# systemctl poweroff
3.2 副机挂载 LVM
我们新建一个虚拟机，以 ubuntu 20.04 为模板。在虚拟机的设置中加上之前的 3 块硬盘。
然后，开机。
见证奇迹的时刻到了！
root@lvm1:~# fdisk -l
Disk /dev/sda: 10 GiB, 10737418240 bytes, 20971520 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 1B9BD938-DE74-4DA8-89D4-BD4F40B6132B
Device Start End Sectors Size Type
/dev/sda1 2048 4095 2048 1M BIOS boot
/dev/sda2 4096 2101247 2097152 1G Linux filesystem
/dev/sda3 2101248 20969471 18868224 9G Linux filesystem
Disk /dev/sdb: 100 GiB, 107374182400 bytes, 209715200 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xb2891594
Device Boot Start End Sectors Size Id Type
/dev/sdb1 63 209715199 209715137 100G 8e Linux LVM
Disk /dev/sdc: 50 GiB, 53687091200 bytes, 104857600 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sdd: 10 GiB, 10737418240 bytes, 20971520 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xc85f08b0
Device Boot Start End Sectors Size Id Type
/dev/sdd1 2048 20971519 20969472 10G 8e Linux LVM
Disk /dev/sde: 10 GiB, 10737418240 bytes, 20971520 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x8c4dd50f
Device Boot Start End Sectors Size Id Type
/dev/sde1 2048 20971519 20969472 10G 8e Linux LVM
Disk /dev/sdf: 10 GiB, 10737418240 bytes, 20971520 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x1fd1315f
Device Boot Start End Sectors Size Id Type
/dev/sdf1 2048 20971519 20969472 10G 8e Linux LVM
Disk /dev/mapper/ubuntu--vg-ubuntu--lv: 64 GiB, 68719476736 bytes, 134217728 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/vg0-lv0: 15 GiB, 16106127360 bytes, 31457280 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
注意观察上表，sdd, sde, sdf 以及 vg0, lv0 都来了！
我们用用看
root@lvm1:~# mount /dev/vg0/lv0 /mnt
root@lvm1:~# ls -alh /mnt
total 32K
drwxr-xr-x 5 root root 4.0K Nov 8 02:30 .
drwxr-xr-x 23 root root 4.0K Sep 14 09:20 ..
drwxr-xr-x 6 root root 4.0K Nov 8 02:20 best
drwx------ 2 root root 16K Nov 8 02:18 lost+found
写点数据进去
root@lvm1:~# git clone secdoc.git
root@lvm1:~# ls -alh /mnt
total 32K
drwxr-xr-x 5 root root 4.0K Nov 8 02:30 .
drwxr-xr-x 23 root root 4.0K Sep 14 09:20 ..
drwxr-xr-x 6 root root 4.0K Nov 8 02:20 best
drwx------ 2 root root 16K Nov 8 02:18 lost+found
drwxr-xr-x 5 root root 4.0K Nov 8 02:30 secdoc
关闭副主机，打开原宿主机，新增的数据赫然在列！
4 结论
- lvm 信息和数据都是写入硬盘的，和主机无关
- 主机对 lvm 只是引用的关系
- 放心大胆地对数据进行 lvm 吧
- 我们可以这样想像，生产环境中的硬盘，是来自光纤存储的