Centos 7分区失败，进入 dracut 页面，恢复操作

1. 问题场景：

分区失败，重启了虚拟机，导致系统进入 dracut 页面。开机显示

直接回车，等待重启失败的页面


自动进入了 dracut 模式(救援)。

2. 临时解决进入系统

查了一下：如果出现 “dracut” 提示、进入 dracut 模式或者

dracut emergency shell

，这可能表示系统无法正常引导或加载根文件系统。

在shell命令行执行以下:

dracut:/# lvm vgscan
dracut:/# lvm vgchange -ay 
dracut:/# exit

这种方式可以临时解决，进入系统（远程SSH 也是正常的）。但是重启之后依然会进入dracut模式。

3. 重新操作分区扩容

由于是分区操作可能没有操作完成就重启了服务器，导致分区异常，启动失败了，那现在可正常进入服务器了，就重新检查下分区。

从磁盘占用情况可以看到，root 目录还是 50G的大小，这是之前创建虚拟机默认的大小。

中可以看到，磁盘总的容量已经扩容到500G了，原来是 200G；

看下当前磁盘分区情况：

fdisk -l

接着使用 fdisk 修改磁盘分区：

fdisk /dev/sda

上面截图就是新增分区的操作：

# 创建分区命令fdisk /dev/sda
再输入p
新增分区输入：n
回车（默认为主分区primary）
分区号、起始扇区、结束扇区都默认（回车）
设置分区格式 直接输入：t
分区号默认（回车）
Hex 代码为 8e （8e代表Linux LVM分区类型）
w （写入分区表）
等待分区完成

这里虽然提示设备或资源忙，忽略这个错误，继续执行 命令：

partprobe

然后参考：VMWare ESXI 给虚拟机硬盘扩容记录（CentOS7） 进行分区合并。

配置分区成功后，在合并分区时：

vgdisplay -v

没有显示新增的分区

sda3

[root@aikg ~]# lvm  
lvm> pvcreate /dev/sda3
WARNING: ext4 signature detected on /dev/sda3 at offset 1080. Wipe it? [y/n]: y
  Wiping ext4 signature on /dev/sda3.
  Physical volume "/dev/sda3" successfully created.
lvm> vgdisplay -v
  --- 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               <199.00 GiB
  PE Size               4.00 MiB
  Total PE              50943
  Alloc PE / Size       50942 / 198.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               7EFuUv-WWlG-kFEM-XDWJ-niAh-iP8A-VxFGya
   
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                wpAfVQ-XL8j-UExO-D6dL-eud3-fLiR-sLejTp
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:04 +0800
  LV Status              available
  # open                 2
  LV Size                <7.88 GiB
  Current LE             2016
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
   
  --- Logical volume ---
  LV Path                /dev/centos/home
  LV Name                home
  VG Name                centos
  LV UUID                KeIjj6-JOO1-aAb1-7eG8-egkk-XCGu-u6FcKw
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:04 +0800
  LV Status              available
  # open                 1
  LV Size                <141.12 GiB
  Current LE             36126
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1
   
  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                0038QM-K8CI-KKFz-0mdD-HyS4-S34U-xFjHL0
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:05 +0800
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2
   
  --- Physical volumes ---
  PV Name               /dev/sda2     
  PV UUID               wwBC0l-n45J-WPZg-frd7-8q5b-ELYx-ONQNtg
  PV Status             allocatable
  Total PE / Free PE    50943 / 1
   
lvm> 
lvm> vgdisplay -v
  --- 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               <199.00 GiB
  PE Size               4.00 MiB
  Total PE              50943
  Alloc PE / Size       50942 / 198.99 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               7EFuUv-WWlG-kFEM-XDWJ-niAh-iP8A-VxFGya
   
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                wpAfVQ-XL8j-UExO-D6dL-eud3-fLiR-sLejTp
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:04 +0800
  LV Status              available
  # open                 2
  LV Size                <7.88 GiB
  Current LE             2016
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
   
  --- Logical volume ---
  LV Path                /dev/centos/home
  LV Name                home
  VG Name                centos
  LV UUID                KeIjj6-JOO1-aAb1-7eG8-egkk-XCGu-u6FcKw
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:04 +0800
  LV Status              available
  # open                 1
  LV Size                <141.12 GiB
  Current LE             36126
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1
   
  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                0038QM-K8CI-KKFz-0mdD-HyS4-S34U-xFjHL0
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:05 +0800
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2
   
  --- Physical volumes ---
  PV Name               /dev/sda2     
  PV UUID               wwBC0l-n45J-WPZg-frd7-8q5b-ELYx-ONQNtg
  PV Status             allocatable
  Total PE / Free PE    50943 / 1
   
lvm> pvcreate /dev/sda3
  Physical volume "/dev/sda3" successfully created.
lvm> 
lvm> vgextend centos /dev/sda3
  Volume group "centos" successfully extended
lvm> 
lvm> vgdisplay -v             
  --- Volume group ---
  VG Name               centos
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               498.99 GiB
  PE Size               4.00 MiB
  Total PE              127742
  Alloc PE / Size       50942 / 198.99 GiB
  Free  PE / Size       76800 / 300.00 GiB
  VG UUID               7EFuUv-WWlG-kFEM-XDWJ-niAh-iP8A-VxFGya
   
  --- Logical volume ---
  LV Path                /dev/centos/swap
  LV Name                swap
  VG Name                centos
  LV UUID                wpAfVQ-XL8j-UExO-D6dL-eud3-fLiR-sLejTp
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:04 +0800
  LV Status              available
  # open                 2
  LV Size                <7.88 GiB
  Current LE             2016
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0
   
  --- Logical volume ---
  LV Path                /dev/centos/home
  LV Name                home
  VG Name                centos
  LV UUID                KeIjj6-JOO1-aAb1-7eG8-egkk-XCGu-u6FcKw
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:04 +0800
  LV Status              available
  # open                 1
  LV Size                <141.12 GiB
  Current LE             36126
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:1
   
  --- Logical volume ---
  LV Path                /dev/centos/root
  LV Name                root
  VG Name                centos
  LV UUID                0038QM-K8CI-KKFz-0mdD-HyS4-S34U-xFjHL0
  LV Write Access        read/write
  LV Creation host, time data-source1, 2021-03-24 14:20:05 +0800
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2
   
  --- Physical volumes ---
  PV Name               /dev/sda2     
  PV UUID               wwBC0l-n45J-WPZg-frd7-8q5b-ELYx-ONQNtg
  PV Status             allocatable
  Total PE / Free PE    50943 / 1
   
  PV Name               /dev/sda3     
  PV UUID               Vb7c4n-aqeD-Kwr5-gkN6-0Zoa-QZVW-gvlmfo
  PV Status             allocatable
  Total PE / Free PE    76799 / 76799
   
lvm>

然后再次操作，新建 pv 后，才显示 sda3 这个物理卷；接着操作扩容根目录：


正常扩容完毕。

接着重启下服务器，发现可以正常启动了。