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
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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。

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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。

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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
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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
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[root@aikg ~]# lvm  
lvm> pvcreate /dev/sda3
WARNING: ext4 signature detected on /dev/sda3 at offset 1080. Wipe it? [y/n]: yWiping ext4 signature on /dev/sda3.Physical volume "/dev/sda3" successfully created.
lvm> vgdisplay -v--- Volume group ---VG Name               centosSystem ID             Format                lvm2Metadata Areas        1Metadata Sequence No  4VG Access             read/writeVG Status             resizableMAX LV                0Cur LV                3Open LV               3Max PV                0Cur PV                1Act PV                1VG Size               <199.00 GiBPE Size               4.00 MiBTotal PE              50943Alloc PE / Size       50942 / 198.99 GiBFree  PE / Size       1 / 4.00 MiBVG UUID               7EFuUv-WWlG-kFEM-XDWJ-niAh-iP8A-VxFGya--- Logical volume ---LV Path                /dev/centos/swapLV Name                swapVG Name                centosLV UUID                wpAfVQ-XL8j-UExO-D6dL-eud3-fLiR-sLejTpLV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:04 +0800LV Status              available# open                 2LV Size                <7.88 GiBCurrent LE             2016Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:0--- Logical volume ---LV Path                /dev/centos/homeLV Name                homeVG Name                centosLV UUID                KeIjj6-JOO1-aAb1-7eG8-egkk-XCGu-u6FcKwLV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:04 +0800LV Status              available# open                 1LV Size                <141.12 GiBCurrent LE             36126Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:1--- Logical volume ---LV Path                /dev/centos/rootLV Name                rootVG Name                centosLV UUID                0038QM-K8CI-KKFz-0mdD-HyS4-S34U-xFjHL0LV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:05 +0800LV Status              available# open                 1LV Size                50.00 GiBCurrent LE             12800Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:2--- Physical volumes ---PV Name               /dev/sda2     PV UUID               wwBC0l-n45J-WPZg-frd7-8q5b-ELYx-ONQNtgPV Status             allocatableTotal PE / Free PE    50943 / 1lvm> 
lvm> vgdisplay -v--- Volume group ---VG Name               centosSystem ID             Format                lvm2Metadata Areas        1Metadata Sequence No  4VG Access             read/writeVG Status             resizableMAX LV                0Cur LV                3Open LV               3Max PV                0Cur PV                1Act PV                1VG Size               <199.00 GiBPE Size               4.00 MiBTotal PE              50943Alloc PE / Size       50942 / 198.99 GiBFree  PE / Size       1 / 4.00 MiBVG UUID               7EFuUv-WWlG-kFEM-XDWJ-niAh-iP8A-VxFGya--- Logical volume ---LV Path                /dev/centos/swapLV Name                swapVG Name                centosLV UUID                wpAfVQ-XL8j-UExO-D6dL-eud3-fLiR-sLejTpLV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:04 +0800LV Status              available# open                 2LV Size                <7.88 GiBCurrent LE             2016Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:0--- Logical volume ---LV Path                /dev/centos/homeLV Name                homeVG Name                centosLV UUID                KeIjj6-JOO1-aAb1-7eG8-egkk-XCGu-u6FcKwLV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:04 +0800LV Status              available# open                 1LV Size                <141.12 GiBCurrent LE             36126Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:1--- Logical volume ---LV Path                /dev/centos/rootLV Name                rootVG Name                centosLV UUID                0038QM-K8CI-KKFz-0mdD-HyS4-S34U-xFjHL0LV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:05 +0800LV Status              available# open                 1LV Size                50.00 GiBCurrent LE             12800Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:2--- Physical volumes ---PV Name               /dev/sda2     PV UUID               wwBC0l-n45J-WPZg-frd7-8q5b-ELYx-ONQNtgPV Status             allocatableTotal PE / Free PE    50943 / 1lvm> pvcreate /dev/sda3Physical volume "/dev/sda3" successfully created.
lvm> 
lvm> vgextend centos /dev/sda3Volume group "centos" successfully extended
lvm> 
lvm> vgdisplay -v             --- Volume group ---VG Name               centosSystem ID             Format                lvm2Metadata Areas        2Metadata Sequence No  5VG Access             read/writeVG Status             resizableMAX LV                0Cur LV                3Open LV               3Max PV                0Cur PV                2Act PV                2VG Size               498.99 GiBPE Size               4.00 MiBTotal PE              127742Alloc PE / Size       50942 / 198.99 GiBFree  PE / Size       76800 / 300.00 GiBVG UUID               7EFuUv-WWlG-kFEM-XDWJ-niAh-iP8A-VxFGya--- Logical volume ---LV Path                /dev/centos/swapLV Name                swapVG Name                centosLV UUID                wpAfVQ-XL8j-UExO-D6dL-eud3-fLiR-sLejTpLV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:04 +0800LV Status              available# open                 2LV Size                <7.88 GiBCurrent LE             2016Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:0--- Logical volume ---LV Path                /dev/centos/homeLV Name                homeVG Name                centosLV UUID                KeIjj6-JOO1-aAb1-7eG8-egkk-XCGu-u6FcKwLV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:04 +0800LV Status              available# open                 1LV Size                <141.12 GiBCurrent LE             36126Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:1--- Logical volume ---LV Path                /dev/centos/rootLV Name                rootVG Name                centosLV UUID                0038QM-K8CI-KKFz-0mdD-HyS4-S34U-xFjHL0LV Write Access        read/writeLV Creation host, time data-source1, 2021-03-24 14:20:05 +0800LV Status              available# open                 1LV Size                50.00 GiBCurrent LE             12800Segments               1Allocation             inheritRead ahead sectors     auto- currently set to     8192Block device           253:2--- Physical volumes ---PV Name               /dev/sda2     PV UUID               wwBC0l-n45J-WPZg-frd7-8q5b-ELYx-ONQNtgPV Status             allocatableTotal PE / Free PE    50943 / 1PV Name               /dev/sda3     PV UUID               Vb7c4n-aqeD-Kwr5-gkN6-0Zoa-QZVW-gvlmfoPV Status             allocatableTotal PE / Free PE    76799 / 76799lvm>