一、 创建逻辑卷：
逻辑卷的创建需要经过三个步骤，第一步创建物理卷pv；第二步创建卷组vg；第三步创建逻辑卷lv。
创建物理卷：
pvcreate /dev/sdb1
pvcreate /dev/sdb2查看物理卷：
pvdisplay创建卷组myvg：
vgcreate myvg /dev/sdb1 /dev/sdb2查看卷组：
vgdisplay
--- Volume group ---
VG Name myvg
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 19.99 GiB
PE Size 4.00 MiB
Total PE 5118
Alloc PE / Size 5118 / 19.99 GiB
Free PE / Size 0 / 0
VG UUID CnG19u-iM81-6RUH-xihJ-UoVQ-6M10-Ix4jfg创建逻辑卷mylv：
把myvg的所有PE全部创建lv：
lvcreate -l 5118 -n mylv /dev/myvg
或者创建指定大小（不能超过vg的大小）的lv
lvcreate -L 10G -n mylv /dev/myvg查看逻辑卷：
lvdisplay挂载逻辑卷：（其挂载方式与普通分区挂载一样）
mount /dev/myvg/mylv /mnt二、逻辑卷的扩容
逻辑卷的底层又卷组组成，所以要扩展逻辑卷就要先扩展卷组容量，而卷组又由物理卷组成，所有要先增加物理卷。
添加新硬盘，并分区
#lsblk 查看新硬盘
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 50G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 49.5G 0 part
├─centos-root 253:0 0 46.5G 0 lvm /
└─centos-swap 253:1 0 3G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk
├─sdb1 8:17 0 8G 0 part
│ └─myvg-mylv 253:2 0 20G 0 lvm
└─sdb2 8:18 0 12G 0 part
└─myvg-mylv 253:2 0 20G 0 lvm
sdc 8:32 0 20G 0 disk
sr0 11:0 1 55.9M 0 rom
分区：
fdisk /dev/sdc创建物理卷pv：
[root@localhost ~]# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created.
[root@localhost ~]# pvcreate /dev/sdc2
Physical volume "/dev/sdc2" successfully created.扩展卷组vg：
[root@localhost ~]# vgextend myvg /dev/sdc1
Volume group "myvg" successfully extended
[root@localhost ~]# vgdisplay myvg
--- Volume group ---
VG Name myvg
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 5
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 3
Act PV 3
VG Size <29.99 GiB
PE Size 4.00 MiB
Total PE 7677
Alloc PE / Size 5118 / 19.99 GiB
Free PE / Size 2559 / <10.00 GiB
VG UUID CnG19u-iM81-6RUH-xihJ-UoVQ-6M10-Ix4jfg扩展逻辑卷lv：
指定增加一定数量的PE到lv中：
[root@localhost ~]# lvextend -l +2559 /dev/myvg/mylv
Size of logical volume myvg/mylv changed from 19.99 GiB (5118 extents) to <29.99 GiB (7677 extents).
Logical volume myvg/mylv successfully resized.或者指定扩展到多少个PE：
[root@localhost ~]# lvextend -l 10000 /dev/myvg/mylv
Size of logical volume myvg/mylv changed from 29.98 GiB (7675 extents) to 39.06 GiB (10000 extents).
Logical volume myvg/mylv successfully resized.或者指定lv大小：
[root@localhost ~]# lvextend -L 29.98G /dev/myvg/mylv
Rounding size to boundary between physical extents: 29.98 GiB.
Size of logical volume myvg/mylv changed from <29.69 GiB (7600 extents) to 29.98 GiB (7675 extents).
Logical volume myvg/mylv successfully resized.同步文件系统：
若为xfs文件系统（必须先挂载）则：
root@localhost ~]# xfs_growfs /dev/myvg/mylv
或者
root@localhost ~]# xfs_growfs /mnt
meta-data=/dev/mapper/myvg-mylv isize=512 agcount=4, agsize=1310208 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=5240832, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 5240832 to 7859200若为ext文件系统（挂载不挂载都可以）则：
[root@localhost ~]# resize2fs /dev/mapper/myvg-mylv
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/mapper/myvg-mylv to 10481664 (4k) blocks.
The filesystem on /dev/mapper/myvg-mylv is now 10481664 blocks long.三、逻辑卷缩容
说明：一般不建议缩容，缩容有风险，可能造成数据丢失，操作之前先进行数据备份！
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