EXSI虚机mount出现‘unknown filesystem type 'LVM2_member'’

# 背景

```
EXSI主机操作系统：麒麟v10
主机1系统异常导致无法访问
需要将主机1的文件保存下来
```

# 报错示例

```

[root@localhost ~]# mount /dev/sdb2 /mnt/
mount: /mnt: unknown filesystem type 'LVM2_member'
```

# 解决办法·

1. 在主机2上挂载磁盘

![](/media/202304/2023-04-25_135803_1522960.060163638711277945.png)

2. 登陆主机操作

安装lvm2
```
yum install lvm2 -y
```

主机磁盘结构如下：
其中:

`sda`是当前主机系统磁盘
`sdb`是故障机的系统磁盘

```
[root@localhost ~]# lsblk
NAME          MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda             8:0    0  50G  0 disk
├─sda1          8:1    0   1G  0 part
└─sda2          8:2    0  49G  0 part
  └─klas-root 253:0    0  49G  0 lvm  /
sdb             8:16   0  50G  0 disk
├─sdb1          8:17   0   1G  0 part /boot
└─sdb2          8:18   0  49G  0 part
```

3.  激活lvm

```
# 激活lvm卷
[root@localhost ~]# modprobe dm-mod
[root@localhost ~]# vgchange -ay
  WARNING: found device with duplicate /dev/sdb2
  WARNING: Disabling lvmetad cache which does not support duplicate PVs.
  WARNING: Scan found duplicate PVs.
  WARNING: Not using lvmetad because cache update failed.
  WARNING: Not using device /dev/sdb2 for PV NBIafH-zGvN-HBH7-kgEO-jceV-tKeZ-22nv1F.
  WARNING: PV NBIafH-zGvN-HBH7-kgEO-jceV-tKeZ-22nv1F prefers device /dev/sda2 because of previous preference.
  1 logical volume(s) in volume group "klas" now active #这里显示active表示激活成功
```

4. 检查激活的lvm

```
[root@localhost ~]# lvscan
  WARNING: found device with duplicate /dev/sdb2
  WARNING: Disabling lvmetad cache which does not support duplicate PVs.
  WARNING: Scan found duplicate PVs.
  WARNING: Not using lvmetad because cache update failed.
  WARNING: Not using device /dev/sdb2 for PV NBIafH-zGvN-HBH7-kgEO-jceV-tKeZ-22nv1F.
  WARNING: PV NBIafH-zGvN-HBH7-kgEO-jceV-tKeZ-22nv1F prefers device /dev/sda2 because of previous preference.
  ACTIVE            '/dev/klas/root' [<49.00 GiB] inherit
[root@localhost ~]# lsblk
```

其中：
 `ACTIVE` 表示激活成功           
 `'/dev/klas/root'` 表示可以挂载的卷
 
>==注意== : 不可选择相同pv卷的主机或复制的主机 
>否则挂载后df不显示，在mnt目录下显示内容属于当前机的系统卷内容

5. 正常挂载

```
[root@localhost ~]# ll /dev/klas/root
lrwxrwxrwx 1 root root 7 Apr 25 13:50 /dev/klas/root -> ../dm-0
[root@localhost ~]# mount /dev/klas/root /mnt
```