C7-磁盘高级管理--LVM逻辑卷管理
1.LVM逻辑卷概念
LVM（Logical Volume Manager）逻辑卷管理，它是Linux环境下对磁盘和分区进行管理的一种机制。
普通的磁盘分区管理方式在分区划分好之后一般无法改变其大小（有风险），当一个分区存放不下文件时，解决的方法通常是使用符号链接，或者使用调整分区大小的工具，但这只是暂时解决办法，没有从根本上解决问题。
2.LVM的组成部分
物理卷（PV，Physical Volume）：由磁盘或分区转化而成
卷组（VG，Volume Group）：将多个物理卷组合在一起组成了卷组，组成同一个卷组的可以是同一个硬盘的不同分区，也可以是不同硬盘上的不同分区，也可以是整块磁盘，我们通常把卷组理解为一块硬盘。
逻辑卷（LV，Logical Volume）：把卷组理解为硬盘的话，那么我们的逻辑卷则是硬盘上的分区，逻辑卷可以进行格式化，存储数据。
物理扩展（PE，Physical Extend）：PE卷组的最小存储单元，PE所在的位置是VG卷组，即硬盘上，那么我们可以把PE理解为硬盘上的扇区，默认是4MB，可自由配置。
3.创建LVM
将磁盘分区，或整块磁盘不分区（不做任何操作）
将磁盘上的分区或整块盘建立成物理卷（PV）
将新增的物理卷组合成卷组（VG），并且可以通过添加或者删除一块物理卷，来实现卷组大小的调整。
最后将卷组划分成逻辑卷（LV），逻辑卷也是可以随意调整大小的，逻辑卷相当于真正的分区，那么要使用必须进行格式化和挂载。
3.1物理卷管理
1）使用gdisk 来进行分区，分区的系统ID需要改为8e00
[root@lianxi ~]# gdisk /dev/sdb
GPT fdisk (gdisk) version 0.8.10
Partition table scan:
MBR: not present
BSD: not present
APM: not present
GPT: not present
Creating new GPT entries.
Command (? for help): n
Partition number (1-128, default 1):
First sector (34-41943006, default = 2048) or {+-}size{KMGTP}:
Last sector (2048-41943006, default = 41943006) or {+-}size{KMGTP}: +15G
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): 8e00
Changed type of partition to 'Linux LVM'
Command (? for help): p
Disk /dev/sdb: 41943040 sectors, 20.0 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 728B3E2E-4FF8-45F8-A517-79134C8BF361
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 41943006
Partitions will be aligned on 2048-sector boundaries
Total free space is 10485693 sectors (5.0 GiB)
Number Start (sector) End (sector) Size Code Name
1 2048 31459327 15.0 GiB 8E00 Linux LVM
Command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/sdb.
The operation has completed successfully.
- 创建物理卷—pvcreate
[root@lianxi ~]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created.
- 查看物理卷—pvscan（简化pvs） & pvdisplay
[root@lianxi ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 lvm2 --- 15.00g 15.00g
[root@lianxi ~]# pvdisplay #查看每一个物理卷的详细信息
--- Physical volume ---
PV Name /dev/sda2
VG Name centos
PV Size <19.00 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 4863
Free PE 0
Allocated PE 4863
PV UUID M4P3J9-VTUh-wH9h-1CrC-XeiU-c2OK-EwlVNL
"/dev/sdb1" is a new physical volume of "15.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 15.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID crWrZd-h4rz-m0hS-vg9v-tZVv-q8jH-ERNzHV
- 删除物理卷—pvremove
[root@lianxi ~]# pvcreate /dev/sdc #先添加一个
Physical volume "/dev/sdc" successfully created.
[root@lianxi ~]# pvs #查看
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 lvm2 --- 15.00g 15.00g
/dev/sdc lvm2 --- 20.00g 20.00g
[root@lianxi ~]# pvremove /dev/sdc #删除
Labels on physical volume "/dev/sdc" successfully wiped.
[root@lianxi ~]# pvs #查看
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 lvm2 --- 15.00g 15.00g
3.2卷组管理
- 创建卷组—vgcreate
格式：vgcreate 选项 卷组名 物理卷(写多个时用空格分开)
-s 大小：指定VG的PE大小
[root@lianxi ~]# vgcreate -s 3M vg1 /dev/sdb1 /dev/sdc
Volume group "vg1" successfully created
- 查看卷组—vgscan（vgs） & vgdisplay
[root@lianxi ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <19.00g 0
vg1 2 0 0 wz--n- <35.00g <35.00g
[root@lianxi ~]# vgdisplay
--- Volume group ---
VG Name centos
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 <19.00 GiB
PE Size 4.00 MiB
Total PE 4863
Alloc PE / Size 4863 / <19.00 GiB
Free PE / Size 0 / 0
VG UUID E9PMme-ueMm-GUxW-wbcf-DB2K-ULEv-cfZuHt
--- Volume group ---
VG Name vg1
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 <35.00 GiB
PE Size 3.00 MiB
Total PE 11945
Alloc PE / Size 0 / 0
Free PE / Size 11945 / <35.00 GiB
VG UUID V4heyX-bBBa-7i2g-c6b4-yzl8-99TU-wKEa4b
- 减小卷组容量–vgreduce
格式：vgreduce 卷组名 物理卷名
[root@lianxi ~]# vgreduce vg1 /dev/sdc
Removed "/dev/sdc" from volume group "vg1"
[root@lianxi ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <19.00g 0
vg1 1 0 0 wz--n- <15.00g <15.00g
拓展：vgreduce -a 卷组 #删除指定卷组内所有空的物理卷
4) 增加卷组容量–vgextend
格式：vgrextend 卷组名 物理卷名
[root@lianxi ~]# vgextend vg1 /dev/sdc
Volume group "vg1" successfully extended
[root@lianxi ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <19.00g 0
vg1 2 0 0 wz--n- <35.00g <35.00g
- 删除卷组—vgremove（若已存数据则谨慎操作）
[root@lianxi ~]# vgremove vg1
Volume group "vg1" successfully removed
[root@lianxi ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <19.00g 0
[root@lianxi ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <19.00g 0
[root@lianxi ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 lvm2 --- 15.00g 15.00g #已经没有了
/dev/sdc lvm2 --- 20.00g 20.00g
3.3逻辑卷管理
- 创建逻辑卷–lvcreate
格式：lvcreate 选项 -n 逻辑卷名 卷组名
-L 容量：指定创建的逻辑卷大小，单位：MB,GB,TB等
-l（小） PE个数：按照PE个数来指定逻辑卷大小
-n 逻辑卷名：指定逻辑卷的名字
[root@lianxi ~]# lvcreate -L 20G -n lv1 vg1
Rounding up size to full physical extent 20.00 GiB
Logical volume "lv1" created
- 查看逻辑卷—lvscan （lvs）& lvdisplay
[root@lianxi ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- <17.00g
swap centos -wi-ao---- 2.00g
lv1 vg1 -wi-a----- 20.00g #创建成功
[root@lianxi ~]# vgs
VG #PV #LV #SN Attr VSize VFree
centos 1 2 0 wz--n- <19.00g 0
vg1 2 1 0 wz--n- <35.00g 14.99g #剩余14.99g可用
[root@lianxi ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 centos lvm2 a-- <19.00g 0
/dev/sdb1 vg1 lvm2 a-- <15.00g 14.99g #剩余14.99g可用
/dev/sdc vg1 lvm2 a-- <20.00g 0 #用完
[root@lianxi ~]# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID A2F3RR-o5PM-hEwI-1FpN-JZe3-Wvgd-LpPjIp
LV Write Access read/write
LV Creation host, time localhost, 2020-04-15 06:01:34 -0400
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/root
LV Name root
VG Name centos
LV UUID juSqQV-iQ2J-NM90-Cuxh-QLvf-kG03-fx9h0k
LV Write Access read/write
LV Creation host, time localhost, 2020-04-15 06:01:35 -0400
LV Status available
# open 1
LV Size <17.00 GiB
Current LE 4351
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/vg1/lv1
LV Name lv1
VG Name vg1
LV UUID 5WhMjS-LCKW-nrmI-ygIt-L9gX-lfBU-AhsjIU
LV Write Access read/write
LV Creation host, time lianxi, 2020-04-23 01:14:51 -0400
LV Status available
# open 0
LV Size 20.00 GiB
Current LE 6827
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
注：因为逻辑卷相当于是分区，所以需要进行格式化和挂载才能使用，并设置自启动
3）格式化、挂载
[root@lianxi ~]# mkfs.xfs /dev/vg1/lv1
meta-data=/dev/vg1/lv1 isize=512 agcount=4, agsize=1310784 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=5243136, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@lianxi ~]# mkdir /lv1
[root@lianxi ~]# mount /dev/vg1/lv1 /lv1
[root@lianxi ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 17G 1.7G 16G 10% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.7M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 133M 882M 14% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 20G 33M 20G 1% /lv1
- 增加逻辑卷容量–lvextend
lvextend -L +10G /dev/vg1/lv1 #先增加lv的大小
xfs_growfs /dev/vg1/lv1 #再修改文件系统的大小
[root@lianxi ~]# lvextend -L +10G /dev/vg1/lv1
Rounding size to boundary between physical extents: 10.00 GiB.
Size of logical volume vg1/lv1 changed from 20.00 GiB (6827 extents) to 30.00 GiB (10241 extents).
Logical volume vg1/lv1 successfully resized.
[root@lianxi ~]# mount /dev/vg1/lv1 /lv1 #重新挂载
mount: /dev/mapper/vg1-lv1 is already mounted or /lv1 busy
/dev/mapper/vg1-lv1 is already mounted on /lv1
[root@lianxi ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 17G 1.7G 16G 10% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.7M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 133M 882M 14% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 20G 33M 20G 1% /lv1 #显示没有加载成功
[root@lianxi ~]# xfs_growfs /dev/vg1/lv1 #所以我们要更新一下
meta-data=/dev/mapper/vg1-lv1 isize=512 agcount=4, agsize=1310784 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=5243136, 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 5243136 to 7865088
[root@lianxi ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 17G 1.7G 16G 10% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.7M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 133M 882M 14% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 30G 33M 30G 1% /lv1 #成功了
- 减小逻辑卷容量—lvreduce
注意：xfs文件系统默认只支持扩容，不支持缩小，so，无法真正做到无损
[root@lianxi ~]# mkdir /word
[root@lianxi ~]# cp -a /dev/vg1/lv1 /word #备份
[root@lianxi ~]# umount /dev/vg1/lv1 #卸载
[root@lianxi ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 17G 1.7G 16G 10% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.7M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 133M 882M 14% /boot
tmpfs 98M 0 98M 0% /run/user/0
[root@lianxi ~]# lvreduce -L 20G /dev/vg1/lv1 #调整大小，默认大小，原来30G，变成20G，
Rounding size to boundary between physical extents: 20.00 GiB.
WARNING: Reducing active logical volume to 20.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce vg1/lv1? [y/n]: y
Size of logical volume vg1/lv1 changed from 30.00 GiB (10241 extents) to 20.00 GiB (6827 extents).
Logical volume vg1/lv1 successfully resized.
[root@lianxi ~]# mkfs.xfs -f /dev/vg1/lv1 #强制更新
meta-data=/dev/vg1/lv1 isize=512 agcount=4, agsize=1310784 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=5243136, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@lianxi ~]# mount /dev/vg1/lv1 /lv1 #重新挂载
[root@lianxi ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 17G 1.7G 16G 10% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.7M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 133M 882M 14% /boot
tmpfs 98M 0 98M 0% /run/user/0
/dev/mapper/vg1-lv1 20G 33M 20G 1% /lv1
[root@lianxi ~]# 数据恢复就可以了