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

讯享网
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：

讯享网# 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  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。