相关概念
1、物理卷(pvcreate):通常一个分区或者一个硬盘就可以建立一个物理卷，物理卷的最小单位是PE,一般默认是4MB。
2、卷组(vgcreate):用于创建LVM卷组。卷组（Volume Group）将多个物理卷组织成一个整体，屏蔽了底层物理卷细节。在卷组上创建逻辑卷时不用考虑具体的物理卷信息。
3、逻辑卷(lvcreate):用于创建LVM的逻辑卷。逻辑卷是创建在卷组之上的。逻辑卷对应的设备文件保存在卷组目录下，例如：在卷组"vg1000"上创建一个逻辑卷"lvol0"，则此逻辑卷对应的设备文件为"/dev/vg1000/lvol0"。
实验开始
[root@server ~]# fdisk -l /dev/sdb
Disk /dev/sdb: 20 GiB, 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
Disklabel type: dos
Disk identifier: 0x1a726657
[root@server ~]#
#分了两个主分区各10G
[root@server ~]# fdisk /dev/sdb
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 20973567 20971520 10G 83 Linux
/dev/sdb2 20973568 41943039 20969472 10G 83 Linux
#创建物理卷
[root@server ~]# pvcreate /dev/sdb1 /dev/sdb2
WARNING: dos signature detected on /dev/sdb2 at offset 510. Wipe it? [y/n]: y
Wiping dos signature on /dev/sdb2.
WARNING: atari signature detected on /dev/sdb2 at offset 466. Wipe it? [y/n]: y
Wiping atari signature on /dev/sdb2.
Physical volume "/dev/sdb1" successfully created.
Physical volume "/dev/sdb2" successfully created.
[root@server ~]#
##查看创建是否成功
[root@server ~]# pvscan
PV /dev/sda2 VG rhel_server lvm2 [<19.00 GiB / 0 free]
PV /dev/sdb1 lvm2 [10.00 GiB]
PV /dev/sdb2 lvm2 [<10.00 GiB]
Total: 3 [<39.00 GiB] / in use: 1 [<19.00 GiB] / in no VG: 2 [<20.00 GiB]
##将物理卷添加到卷组，这里暂时只添加了/dev/sdb1的一个分区
[root@server ~]# vgcreate vg1 /dev/sdb1
Volume group "vg1" successfully created
##pvs查看加入的情况
[root@server ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 rhel_server lvm2 a-- <19.00g 0
/dev/sdb1 vg1 lvm2 a-- <10.00g <10.00g
/dev/sdb2 lvm2 --- <10.00g <10.00g
#在卷组Vg1下创建data并分配8G空间给到逻辑data
[root@server ~]# lvcreate -n data -L 8G vg1
WARNING: ext4 signature detected on /dev/vg1/data at offset 1080. Wipe it? [y/n]: y
Wiping ext4 signature on /dev/vg1/data.
Logical volume "data" created.
[root@server ~]#
#将磁盘格式化为ext4类型
[root@server ~]# mkfs.ext4 /dev/vg1/data
mke2fs 1.44.3 (10-July-2018)
Creating filesystem with 2097152 4k blocks and 524288 inodes
Filesystem UUID: 3e9d17d5-f6f8-459e-bcdc-b0a4805fffbf
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
[root@server ~]#
##然后挂载就可以使用了
[root@server ~]# mount /dev/vg1/data /root/data
[root@server ~]# df -Th | grep data
/dev/mapper/vg1-data ext4 7.9G 36M 7.4G 1% /root/data
##假如data空间不够用了，这时候就要开始扩容了，将/dev/sdb2加入卷组Vg1
[root@server ~]# vgextend vg1 /dev/sdb2
Volume group "vg1" successfully extended
##查看剩余空间
[root@server ~]# vgs
VG #PV #LV #SN Attr VSize VFree
rhel_server 1 2 0 wz--n- <19.00g 0
vg1 2 1 0 wz--n- 19.99g 11.99g
#在线扩容将data增加多5G的空间
[root@server ~]# lvextend /dev/vg1/data -L +5G
Size of logical volume vg1/data changed from 8.00 GiB (2048 extents) to 13.00 GiB (3328 extents).
Logical volume vg1/data successfully resized.
[root@server ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root rhel_server -wi-ao---- <17.00g
swap rhel_server -wi-ao---- 2.00g
data vg1 -wi-ao---- 13.00g
#因为扩容后没有格式化所以在文件系统上查看不到
[root@server ~]# df -Th | grep data
/dev/mapper/vg1-data ext4 7.9G 36M 7.4G 1% /root/data
#将扩容的空间加入到data文件系统上, resize2fs :针对文件系统ext2 ext3 ext4 xfs_growfs:针对文件系统xfs
[root@server ~]# resize2fs /dev/vg1/data
resize2fs 1.44.3 (10-July-2018)
Filesystem at /dev/vg1/data is mounted on /root/data; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 2
The filesystem on /dev/vg1/data is now 3407872 (4k) blocks long.
[root@server ~]# df -Th | grep data
/dev/mapper/vg1-data ext4 13G 40M 13G 1% /root/data
[root@server ~]#
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