LVM2:
LVM: Logical Volume Manager， Version: 2
dm: device mapper（设备映射），将一个或多个底层块设备组织成一个逻辑设备的模块；
/dev/dm-#
/dev/mapper/VG_NAME-LV_NAME
如：/dev/mapper/vol0-root
符号链接：/dev/VG_NAME/LV_NAME
如：/dev/vol0/root
[root@promote ~]# cd /dev/mapper
[root@promote mapper]# ll
total 0
lrwxrwxrwx. 1 root root 7 Apr 11 21:37 centos-home -> ../dm-2
lrwxrwxrwx. 1 root root 7 Apr 11 21:37 centos-root -> ../dm-0
lrwxrwxrwx. 1 root root 7 Apr 11 21:37 centos-swap -> ../dm-1
crw-------. 1 root root 10, 236 Apr 11 21:37 control
pv（物理卷）管理工具：
pvs：简要pv信息显示
[root@promote ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos_promote lvm2 a-- <199.00g 4.00m
pvdisplay：显示pv的详细信息
[root@promote ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name centos_promote
PV Size <199.00 GiB / not usable 3.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 50943
Free PE 1
Allocated PE 50942
PV UUID M6rkVy-FZMk-girX-Vul7-FEcN-sJS6-xDwcvU
pvcreate /dev/DEVICE: 创建pv
vg（卷组）管理工具：
vgs：简要显示vg信息
[root@promote ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos_promote 1 3 0 wz--n- <199.00g 4.00m
vgdisplay：显示vg的详细信息
[root@promote ~]# vgdisplay
--- Volume group ---
VG Name centos_promote
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <199.00 GiB
PE Size 4.00 MiB
Total PE 50943
Alloc PE / Size 50942 / 198.99 GiB
Free PE / Size 1 / 4.00 MiB
VG UUID fH4Oc1-iVlL-HJqs-HtcU-2XNA-wSch-V7laxn
vgcreate [-s #[kKmMgGtTpPeE]] VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
vgextend VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
vgreduce VolumeGroupName PhysicalDevicePath [PhysicalDevicePath...]
先做pvmove vgremove
lv（逻辑卷）管理工具：
lvs：简要显示lv信息
[root@promote ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
home centos_promote -wi-ao---- 146.99g
root centos_promote -wi-ao---- 50.00g
swap centos_promote -wi-ao---- 2.00g
lvdisplay：显示lv的详细信息
[root@promote ~]# lvdisplay
--- Logical volume ---
LV Path /dev/centos_promote/swap
LV Name swap
VG Name centos_promote
LV UUID Xcy2JA-IZ6C-0jC2-VkBK-TXLL-PEOv-bSnTNc
LV Write Access read/write
LV Creation host, time promote.cache-dns.local, 2019-04-11 21:52:32 +0800
LV Status available
# open 2
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos_promote/home
LV Name home
VG Name centos_promote
LV UUID tpMG5K-GlWc-o8qX-gtoa-46xv-eQSs-Hktet3
LV Write Access read/write
LV Creation host, time promote.cache-dns.local, 2019-04-11 21:52:32 +0800
LV Status available
# open 1
LV Size 146.99 GiB
Current LE 37630
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/centos_promote/root
LV Name root
VG Name centos_promote
LV UUID jMtc29-aRsN-bXIi-SZyG-aEdJ-3WTk-yX7QAN
LV Write Access read/write
LV Creation host, time promote.cache-dns.local, 2019-04-11 21:52:32 +0800
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
lvcreate -L #[mMgGtT] -n NAME VolumeGroup
lvremove /dev/VG_NAME/LV_NAME
扩展逻辑卷：
# lvextend -L [+]#[mMgGtT] /dev/VG_NAME/LV_NAME 扩展物理边界
# resize2fs /dev/VG_NAME/LV_NAME 扩展逻辑边界
缩减逻辑卷：
# umount /dev/VG_NAME/LV_NAME
# e2fsck -f /dev/VG_NAME/LV_NAME
# resize2fs /dev/VG_NAME/LV_NAME #[mMgGtT]
# lvreduce -L [-]#[mMgGtT] /dev/VG_NAME/LV_NAME
# mount
快照：snapshot
lvcreate -L #[mMgGtT] -p r -s -n snapshot_lv_name original_lv_name
[root@localhost ~]# mount /dev/myvg/mylv /mydata/
[root@localhost ~]# lvcreate -L 10G -s -n mysnap /dev/myvg/mylv
Using default stripesize 64.00 KiB.
Logical volume "mysnap" created.
[root@localhost ~]# mount /dev/myvg/mysnap /snap/
练习：
1、创建一个10G的卷组，取名给myvg，PE大小为16MB
[root@localhost ~]# fdisk -l /dev/sdd
磁盘 /dev/sdd：21.5 GB, 21474836480 字节，41943040 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0x2a039123
设备 Boot Start End Blocks Id System
/dev/sdd1 2048 10487807 5242880 8e Linux LVM
/dev/sdd2 10487808 20973567 5242880 8e Linux LVM
/dev/sdd3 20973568 31459327 5242880 8e Linux LVM
/dev/sdd4 31459328 41943039 5241856 8e Linux LVM
[root@localhost ~]# pvcreate /dev/sdd{1,2}
Physical volume "/dev/sdd1" successfully created
Physical volume "/dev/sdd2" successfully created
[root@localhost ~]# vgcreate -s 16M myvg /dev/sdd{1,2}
Volume group "myvg" successfully created
[root@localhost ~]# vgdisplay myvg
--- Volume group ---
VG Name myvg
System ID
Format lvm2
Metadata Areas 2
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 2
Act PV 2
VG Size 9.97 GiB
PE Size 16.00 MiB
Total PE 638
Alloc PE / Size 0 / 0
Free PE / Size 638 / 9.97 GiB
VG UUID RpVYYx-SsPF-2h7l-9hlW-FXMf-ti5T-iCytfw
2、创建一个逻辑卷，取名为mylv，大小为5G。
[root@localhost ~]# lvcreate -L 5G -n mylv myvg
Logical volume "mylv" created.
3、为卷组myvg新增一个分区，扩展其大小为15G；
[root@localhost ~]# pvcreate /dev/sdd{3,4}
Physical volume "/dev/sdd3" successfully created.
Physical volume "/dev/sdd4" successfully created.
[root@localhost ~]# vgextend myvg /dev/sdd3
Volume group "myvg" successfully extended
[root@localhost ~]# vgdisplay myvg
--- Volume group ---
VG Name myvg
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 4
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 14.95 GiB
PE Size 16.00 MiB
Total PE 957
Alloc PE / Size 320 / 5.00 GiB
Free PE / Size 637 / 9.95 GiB
VG UUID RpVYYx-SsPF-2h7l-9hlW-FXMf-ti5T-iCytfw
4、在格式化挂载逻辑卷mylv之后，尝试扩展逻辑卷mylv大小为10G；
[root@localhost ~]# df -lh
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 18G 4.8G 13G 28% /
.....
/dev/mapper/myvg-mylv 4.8G 66M 4.5G 2% /mydata
[root@localhost ~]# umount /mydata
[root@localhost ~]# lvextend -L +5G /dev/myvg/mylv
Size of logical volume myvg/mylv changed from 5.00 GiB (320 extents) to 10.00 GiB (640 extents).
Logical volume myvg/mylv successfully resized.
[root@localhost ~]# resize2fs /dev/myvg/mylv
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/myvg/mylv to 2621440 (4k) blocks.
The filesystem on /dev/myvg/mylv is now 2621440 blocks long.
[root@localhost ~]# lvdisplay /dev/myvg/mylv
--- Logical volume ---
LV Path /dev/myvg/mylv
LV Name mylv
VG Name myvg
LV UUID LUVw2b-hxTp-nMWh-swgU-n62l-hSL3-QVUoEY
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2018-03-08 20:48:31 +0800
LV Status available
# open 0
LV Size 10.00 GiB
Current LE 640
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:6
5、使用快照备份对应的逻辑卷内容，备份完成会后，删除快照；
[root@localhost ~]# tar Jcf snaptest.tar.xz /snap/*
tar: 从成员名中删除开头的“/”
[root@localhost ~]# ll snaptest.tar.xz
-rw-r--r--. 1 root root 7820112 3月 8 21:11 snaptest.tar.xz
[root@localhost ~]# umount /snap/
[root@localhost ~]# lvremove /dev/myvg/mysnap
Do you really want to remove active logical volume myvg/mysnap? [y/n]: y
Logical volume "mysnap" successfully removed
6、缩减逻辑卷mylv的大小为6G；
root@localhost ~]# umount /dev/myvg/mylv
[root@localhost ~]# e2fsck -f /dev/myvg/mylv
e2fsck 1.42.9 (28-Dec-2013)
第一步: 检查inode,块,和大小
第二步: 检查目录结构
第3步: 检查目录连接性
Pass 3A: Optimizing directories
Pass 4: Checking reference counts
第5步: 检查簇概要信息
/dev/myvg/mylv: ***** 文件系统已修改 *****
/dev/myvg/mylv: 3722/655360 files (0.1% non-contiguous), 91436/2621440 blocks
[root@localhost ~]# resize2fs /dev/myvg/mylv 6G
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/myvg/mylv to 1572864 (4k) blocks.
The filesystem on /dev/myvg/mylv is now 1572864 blocks long.
[root@localhost ~]# lvreduce -L 6G /dev/myvg/mylv
WARNING: Reducing active logical volume to 6.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce myvg/mylv? [y/n]: y
Size of logical volume myvg/mylv changed from 10.00 GiB (640 extents) to 6.00 GiB (384 extents).
Logical volume myvg/mylv successfully resized.
root@localhost ~]# mount /dev/myvg/mylv /mydata/
[root@localhost ~]# head -n 2 /mydata/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
7、删除逻辑卷，卷组及物理卷
[root@localhost ~]# umount /mydata/
[root@localhost ~]# lvremove /dev/myvg/mylv
Do you really want to remove active logical volume myvg/mylv? [y/n]: y
Logical volume "mylv" successfully removed
[root@localhost ~]# vgremove /dev/myvg
Volume group "myvg" successfully removed
[root@localhost ~]# pvremove /dev/sdd{1,2,3,4}
Labels on physical volume "/dev/sdd1" successfully wiped.
Labels on physical volume "/dev/sdd2" successfully wiped.
Labels on physical volume "/dev/sdd3" successfully wiped.
Labels on physical volume "/dev/sdd4" successfully wiped.
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