挂载已有数据的LVM磁盘

客户的centos虚拟机无法进入系统，但里面的数据很重要，所以新建一个centos虚拟机来挂载故障虚拟机的lvm磁盘

1.新建虚拟机后先开机进系统，然后再挂载旧磁盘

2.用fdisk -l 查看磁盘情况，能识别到旧磁盘sdb

[root@localhost ~]# fdisk -l

Disk /dev/sda: 536.9 GB, 536870912000 bytes, 1048576000 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 label type: dos
Disk identifier: 0x000c5f9d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200  1048575999   523238400   8e  Linux LVM

Disk /dev/mapper/centos-root: 53.7 GB, 53687091200 bytes, 104857600 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/centos-swap: 8455 MB, 8455716864 bytes, 16515072 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/centos-home: 473.6 GB, 473645973504 bytes, 925089792 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/sdb: 536.9 GB, 536870912000 bytes, 1048576000 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 label type: dos
Disk identifier: 0x000b090b

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048     2099199     1048576   83  Linux
/dev/sdb2         2099200  1048575999   523238400   8e  Linux LVM

3.扫出sdb上的vg卷，发现新系统的VG卷和旧磁盘的VG卷是同名的

[root@localhost ~]# vgscan
  Reading volume groups from cache.
  Found volume group "centos" using metadata type lvm2
  Found volume group "centos" using metadata type lvm2

4.vgdisplay查看vg uuid，因为VG卷名相同，所以只能用VG UUID来更改卷名，随意更改一个vg卷名，以作区分

[root@localhost ~]# vgdisplay
  --- Volume group ---
  VG Name               centos
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               <499.00 GiB
  PE Size               4.00 MiB
  Total PE              127743
  Alloc PE / Size       127742 / 498.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               dEgXW8-PsYd-1t6H-JNu5-sgcg-2K3l-EwXMtc

  --- Volume group ---
  VG Name               centos
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               <499.00 GiB
  PE Size               4.00 MiB
  Total PE              127743
  Alloc PE / Size       127742 / 498.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               YIk6Ds-MsxE-mwek-1x3S-uzdT-lxUo-VFxnGs

[root@localhost ~]# vgrename YIk6Ds-MsxE-mwek-1x3S-uzdT-lxUo-VFxnGs vg01
  Processing VG centos because of matching UUID YIk6Ds-MsxE-mwek-1x3S-uzdT-lxUo-VFxnGs
  Volume group "YIk6Ds-MsxE-mwek-1x3S-uzdT-lxUo-VFxnGs" successfully renamed to "vg01"

5.扫出未激活的那个lvm，并激活，可以看到我刚才改的卷是新系统的卷，所以我现在需要激活旧磁盘上的卷

[root@localhost ~]# lvscan
  inactive          '/dev/centos/swap' [<7.88 GiB] inherit
  inactive          '/dev/centos/home' [<441.12 GiB] inherit
  inactive          '/dev/centos/root' [50.00 GiB] inherit
  ACTIVE            '/dev/vg01/swap' [<7.88 GiB] inherit
  ACTIVE            '/dev/vg01/home' [<441.12 GiB] inherit
  ACTIVE            '/dev/vg01/root' [50.00 GiB] inherit
  
[root@localhost ~]# vgchange -ay /dev/centos
  3 logical volume(s) in volume group "centos" now active

6.新建一个挂载点并挂载旧磁盘的卷，让软件方copy数据，根据网上的资料，需要挂载的是、/dev/centos/root这个目录，据说挂载home会有问题

[root@localhost ~]# mkdir /mnt/olddisk

[root@localhost ~]# mount /dev/centos/root /mnt/olddisk