逻辑卷解决的问题为动态调整磁盘空间的大小，而实现这个功能的关键在于逻辑卷可以动态的调整大小。
只要卷组中有足够的存储资源，就可以对逻辑卷扩容
1、查看系统中当前的逻辑卷
[root@PC1linuxprobe dev]# lvscan
ACTIVE '/dev/rhel/swap' [2.00 GiB] inherit
ACTIVE '/dev/rhel/root' [17.51 GiB] inherit
ACTIVE '/dev/vg1/lv1' [100.00 MiB] inherit
ACTIVE '/dev/vg1/lv2' [200.00 MiB] inherit
由上可知逻辑卷lv1的大小为100Mb，逻辑卷lv2的大小为200Mb。
2、查看系统中当前的卷组
[root@PC1linuxprobe dev]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "rhel" using metadata type lvm2
Found volume group "vg1" using metadata type lvm2
[root@PC1linuxprobe dev]# vgdisplay
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 19.51 GiB
PE Size 4.00 MiB
Total PE 4994
Alloc PE / Size 4994 / 19.51 GiB
Free PE / Size 0 / 0
VG UUID UWd4dl-0vSA-zern-l7on-XLj0-e3cR-AHmckC
--- Volume group ---
VG Name vg1
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 0
Max PV 0
Cur PV 3
Act PV 3
VG Size 59.99 GiB
PE Size 4.00 MiB
Total PE 15357
Alloc PE / Size 75 / 300.00 MiB
Free PE / Size 15282 / 59.70 GiB
VG UUID Bjeykx-Lulw-rdC5-s1MV-9MSE-5G1y-hbYaHl
由上可知，卷组vg1的大小剩余为59.70 GiB。
3、扩容逻辑卷前，解除逻辑卷与挂载点的关联，即卸载，上一个实验未挂载，因此此处省略卸载
[root@PC1linuxprobe dev]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 18G 2.9G 15G 17% /
devtmpfs 985M 0 985M 0% /dev
tmpfs 994M 140K 994M 1% /dev/shm
tmpfs 994M 8.9M 986M 1% /run
tmpfs 994M 0 994M 0% /sys/fs/cgroup
/dev/sda1 497M 119M 379M 24% /boot
/dev/sr0 3.5G 3.5G 0 100% /run/media/root/RHEL-7.0 Server.x86_64
4、将逻辑卷lv2的大小由200Mb扩容为500Mb。
[root@PC1linuxprobe dev]# lvscan
ACTIVE '/dev/rhel/swap' [2.00 GiB] inherit
ACTIVE '/dev/rhel/root' [17.51 GiB] inherit
ACTIVE '/dev/vg1/lv1' [100.00 MiB] inherit
ACTIVE '/dev/vg1/lv2' [200.00 MiB] inherit
[root@PC1linuxprobe dev]# lvextend -L 500M /dev/vg1/lv2
Extending logical volume lv2 to 500.00 MiB
Logical volume lv2 successfully resized
[root@PC1linuxprobe dev]# lvscan
ACTIVE '/dev/rhel/swap' [2.00 GiB] inherit
ACTIVE '/dev/rhel/root' [17.51 GiB] inherit
ACTIVE '/dev/vg1/lv1' [100.00 MiB] inherit
ACTIVE '/dev/vg1/lv2' [500.00 MiB] inherit
5、检查硬盘完整性（未通过，上一个实验没有挂载，也就没有格式化为exf4文件系统）
[root@PC1linuxprobe dev]# e2fsck -f /dev/vg1/lv2
e2fsck 1.42.9 (28-Dec-2013)
ext2fs_open2: Bad magic number in super-block
e2fsck: Superblock invalid, trying backup blocks...
e2fsck: Bad magic number in super-block while trying to open /dev/vg1/lv2
The superblock could not be read or does not describe a correct ext2
filesystem. If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
6、将逻辑卷lv2格式化ext4文件系统
[root@PC1linuxprobe dev]# mkfs.ext4 /dev/vg1/lv2
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
128016 inodes, 512000 blocks
25600 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=34078720
63 block groups
8192 blocks per group, 8192 fragments per group
2032 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
6、再次检查磁盘的完整性
[root@PC1linuxprobe dev]# e2fsck -f /dev/vg1/lv2
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg1/lv2: 11/128016 files (0.0% non-contiguous), 26684/512000 blocks
7、重置磁盘容量
[root@PC1linuxprobe dev]# resize2fs /dev/vg1/lv2
resize2fs 1.42.9 (28-Dec-2013)
The filesystem is already 512000 blocks long. Nothing to do!
8、挂载
[root@PC1linuxprobe dev]# mkdir /lvmounttest
[root@PC1linuxprobe dev]# mount /dev/vg1/lv2 /lvmounttest/
[root@PC1linuxprobe dev]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 18G 2.9G 15G 17% /
devtmpfs 985M 0 985M 0% /dev
tmpfs 994M 140K 994M 1% /dev/shm
tmpfs 994M 8.9M 986M 1% /run
tmpfs 994M 0 994M 0% /sys/fs/cgroup
/dev/sda1 497M 119M 379M 24% /boot
/dev/sr0 3.5G 3.5G 0 100% /run/media/root/RHEL-7.0 Server.x86_64
/dev/mapper/vg1-lv2 477M 2.3M 445M 1% /lvmounttest
总结：扩容逻辑卷
- 卸载（解除逻辑卷与挂载点的关联）】
- 扩容，示例：lvextend -L xxM /dev/vg1/lv1
- 格式化为exf4文件系统，示例：mkfs.exf4 /dev/vg1/lv1
- 检查文件系统的完整性，示例：e2fsck -f /dev/vg1/lv1
- 重置逻辑卷大小，示例：resize2fs /dev/vg1/lv1
- 重新挂载
注：逻辑卷扩容后（lvextend）之后，还要检查文件系统的完整性，重置逻辑卷容量，才可以挂载使用