LVM逻辑卷操作实录
之前讲了LVM基础详细说明，现在记录下LVM逻辑卷的操作实录。
一、准备物理分区（Physical Partions）
首先，我们需要选择用于 LVM 的物理存储器。这些通常是标准分区，但也可以是已创建的 Linux Software RAID 卷。这里我利用fdisk命令，将sdb、sdc两块磁盘分了两个区sdb1、sdc1， 通过fdisk的t指令指定分区为8e类型(Linux LVM) ，如下：
[root@localhost ~]# fdisk -l
Disk /dev/sda: 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 label type: dos
Disk identifier: 0x00099e91
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 104857599 52427776 83 Linux
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x8c6de33b
Device Boot Start End Blocks Id System
/dev/sdb1 2048 41943039 20970496 8e Linux LVM
Disk /dev/sdc: 32.2 GB, 32212254720 bytes, 62914560 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: 0xe60d5065
Device Boot Start End Blocks Id System
/dev/sdc1 2048 62914559 31456256 8e Linux LVM
二、创建物理卷PV（Physical Volumes）
[root@localhost ~]# pvcreate /dev/sdb1 # 如果没有pvcreate\命令，可以使用yum install -y lvm2进行安装
Physical volume "/dev/sdb1" successfully created.
[root@localhost ~]# pvcreate /dev/sdc1 #可以使用pcvreate /dev/{sdb1,sdc1}
Physical volume "/dev/sdc1" successfully created.
三、创建卷组VG（Volume Groups）,命名为vg_test1
[root@localhost ~]# vgcreate vg_test1 /dev/sdb1
Volume group "vg_test1" successfully created
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name vg_test1
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size <20.00 GiB
PE Size 4.00 MiB
Total PE 5119
Alloc PE / Size 0 / 0
Free PE / Size 5119 / <20.00 GiB
VG UUID o8efai-0E75-XBW3-Oaxn-pIf3-BiLS-SpAAD3
四、创建逻辑卷LV（Logical Volumes） ,命名为lv_test1
创建逻辑卷的命令为lvcreate，-l 参数为定PE数来设定逻辑分区大小，也可以使用-L参数直接指定逻辑分区大小，-n参数指定逻辑分区名称。
[root@localhost ~]# lvcreate -L 10G -n lv_test1 vg_test1
Logical volume "lv_test1" created.
[root@localhost ~]# lvdisplay
--- Logical volume ---
LV Path /dev/vg_test1/lv_test1
LV Name lv_test1
VG Name vg_test1
LV UUID zcIjip-NOAH-zNyI-lPrB-1f44-wHoi-cgtTSz
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2019-07-05 15:22:45 +0800
LV Status available
# open 0
LV Size 10.00 GiB
Current LE 2560
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
五、创建文件系统并挂载
在逻辑卷上创建ext4文件系统:
[root@localhost ~]# mkfs -t ext4 /dev/vg_test1/lv_test1 # 可以直接使用mkfs.ext4进行格式化
[root@localhost ~]# mount /dev/vg_test1/lv_test1 /data/
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 50G 1.5G 49G 3% /
devtmpfs 903M 0 903M 0% /dev
tmpfs 912M 0 912M 0% /dev/shm
tmpfs 912M 8.6M 904M 1% /run
tmpfs 912M 0 912M 0% /sys/fs/cgroup
tmpfs 183M 0 183M 0% /run/user/0
/dev/mapper/vg_test1-lv_test1 9.8G 37M 9.2G 1% /data
六、动态调整LVM分区大小
LVM的最大好处就是可以动态地调整分区大小，而无须重新启动，下面让我们来体验一下吧！
继续上面的实例，现假设逻辑卷 /dev/vg_test1/lv_test1空间不足，需要增加其大小，我们分两种情况讨论：
1、当卷组中有剩余的空间
通过vgdisplay命令可以检查当前卷组空间使用情况:
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name vg_test1
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 1
Act PV 1
VG Size <20.00 GiB
PE Size 4.00 MiB
Total PE 5119
Alloc PE / Size 2560 / 10.00 GiB
Free PE / Size 2559 / <10.00 GiB
VG UUID o8efai-0E75-XBW3-Oaxn-pIf3-BiLS-SpAAD3
确定当前卷组剩余空间10GB，剩余PE数量为2559个。在这里将所有的剩余空间全部增加给逻辑卷 /dev/vg_test1/lv_test1
[root@localhost ~]# lvextend -l +2559 /dev/vg_test1/lv_test1
Size of logical volume vg_test1/lv_test1 changed from 10.00 GiB (2560 extents) to <20.00 GiB (5119 extents).
Logical volume vg_test1/lv_test1 successfully resized.
修改逻辑卷大小后，通过resize2fs来修改文件系统的大小：
[root@localhost ~]# resize2fs /dev/vg_test1/lv_test1
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/vg_test1/lv_test1 is mounted on /data; on-line resizing required
old_desc_blocks = 2, new_desc_blocks = 3
The filesystem on /dev/vg_test1/lv_test1 is now 5241856 blocks long.
再次查看文件系统的大小：
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 50G 1.5G 49G 3% /
devtmpfs 903M 0 903M 0% /dev
tmpfs 912M 0 912M 0% /dev/shm
tmpfs 912M 8.6M 904M 1% /run
tmpfs 912M 0 912M 0% /sys/fs/cgroup
tmpfs 183M 0 183M 0% /run/user/0
/dev/mapper/vg_test1-lv_test1 20G 44M 19G 1% /data
2、当卷组中空间不足时
当卷组中没有足够的空间用于扩展逻辑卷的大小时，就需要增加卷组的容量，而增加卷组容量的唯一办法就是向卷组中添加新的物理卷。
首先需要对新增加的磁盘进行分区、创建物理卷等工作，接下来是利用vgextend命令将新的物理卷加入到卷组中, 这里使用/dev/sdc1。
[root@localhost ~]# vgextend vg_test1 /dev/sdc1
Volume group "vg_test1" successfully extended
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name vg_test1
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 49.99 GiB
PE Size 4.00 MiB
Total PE 12798
Alloc PE / Size 5119 / <20.00 GiB
Free PE / Size 7679 / <30.00 GiB
VG UUID o8efai-0E75-XBW3-Oaxn-pIf3-BiLS-SpAAD3
对逻辑卷进行扩容
[root@localhost ~]# lvextend -L +20G /dev/vg_test1/lv_test1
Size of logical volume vg_test1/lv_test1 changed from <20.00 GiB (5119 extents) to <40.00 GiB (10239 extents).
Logical volume vg_test1/lv_test1 successfully resized.
修改逻辑卷大小后，通过resize2fs来修改文件系统的大小：
[root@localhost ~]# resize2fs /dev/vg_test1/lv_test1
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/vg_test1/lv_test1 is mounted on /data; on-line resizing required
old_desc_blocks = 3, new_desc_blocks = 5
The filesystem on /dev/vg_test1/lv_test1 is now 10484736 blocks long.
再次查看文件系统的大小：
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 50G 1.5G 49G 3% /
devtmpfs 903M 0 903M 0% /dev
tmpfs 912M 0 912M 0% /dev/shm
tmpfs 912M 8.6M 904M 1% /run
tmpfs 912M 0 912M 0% /sys/fs/cgroup
tmpfs 183M 0 183M 0% /run/user/0
/dev/mapper/vg_test1-lv_test1 40G 48M 38G 1% /data
参考文章：https://www.cnblogs.com/kevingrace/p/5845634.html