服务器出现磁盘空间不足，可通过lvm实现在线扩容lsblk分析服务器磁盘基本情况

使用lsblk 命令查看到我们的分区情况，从下面可以看出服务器的根分区是一个lvm卷，满足在线扩容的要求，同时可发现这台服务器上有三块磁盘sda,sdb,sdc

看看服务器分区挂载情况，根分区挂载名为/dev/mapper/centos-root，当根分区出现磁盘空间不足的时候，我们就可以使用lvm技术在线扩容

查看服务器上有哪些lvm卷，截图中可以看出服务器有两个lvm，/dev/centos/root 就是对应上面截图的centos-root，这个lvm 所属的vg为centos

通过如下命令，可查看服务有哪些vg，Free PE/Size 代表还有多少剩余空间可划分到lvm中

Lvm扩容案例现在开始关闭服务器，添加一块新磁盘，容量10G，添加完成后，开启服务器验证服务器是否已经正常识别到新磁盘,下图可知新磁盘已添加至服务器创建pv，并查看pv

 #创建pv [root@localhost ~]# pvcreate  /dev/sdd  Physical volume "/dev/sdd" successfully created.    #查看pv  [root@localhsot ~]# pvdisplay  /dev/sdd  "/dev/sdd" is a new physical volume of "10.00 GiB"  --- NEW Physical volume ---  PV Name               /dev/sdd  VG Name                 PV Size               10.00 GiB  Allocatable           NO  PE Size               0     Total PE              0  Free PE               0  Allocated PE          0  PV UUID               Ol8Jwp-dGGI-yggZ-l2hB-IDy1-KE25-bEvElV

将pv /dev/sdd 添加至vg

#将pv添加至vg centos[root@localhost ~]# vgextend centos /dev/sdd  Volume group "centos" successfully extended#vg 扩容成功，   Free  PE / Size       2559 / <10.00 GiB 有可用空间[root@localhost ~]# vgdisplay   --- Volume group ---  VG Name               centos  System ID               Format                lvm2  Metadata Areas        4  Metadata Sequence No  8  VG Access             read/write  VG Status             resizable  MAX LV                0  Cur LV                2  Open LV               1  Max PV                0  Cur PV                4  Act PV                4  VG Size               89.98 GiB  PE Size               4.00 MiB  Total PE              23036  Alloc PE / Size       20477 / <79.99 GiB  Free  PE / Size       2559 / <10.00 GiB  VG UUID               gmhCKp-RgpG-XWOv-lj0B-OsRz-YfKm-gsMP81

扩容lvm /dev/centos/root

#扩容lvm,此时根分区总容量并没有增加[root@localhost ~]# lvextend  -l +2559 /dev/centos/root  Size of logical volume centos/root changed from <77.99 GiB (19965 extents) to 87.98 GiB (22524 extents).  Logical volume centos/root successfully resized.  #使扩容生效，真正增加根分区容量[root@localhost ~]# xfs_growfs  /dev/centos/rootmeta-data=/dev/mapper/centos-root isize=512    agcount=7, agsize=3014400 blks         =                       sectsz=512   attr=2, projid32bit=1         =                       crc=1        finobt=0 spinodes=0data     =                       bsize=4096   blocks=20444160, imaxpct=25         =                       sunit=0      swidth=0 blksnaming   =version 2              bsize=4096   ascii-ci=0 ftype=1log      =internal               bsize=4096   blocks=5887, version=2         =                       sectsz=512   sunit=0 blks, lazy-count=1realtime =none                   extsz=4096   blocks=0, rtextents=0data blocks changed from 20444160 to 23064576

查看磁盘分区容量，根分区由直接78G扩容到88G，此次扩容已完成lvm扩容顺序: 增加新磁盘->创建pv(pvcreate)->扩容vg(vgextend)->扩容lvm(lvextend)->扩容生效( xfs_growfs)