LVM
LVM是邏輯盤卷管理（Logical Volume Manager）的簡稱，它是Linux環境下對磁盤分區進行管理的一種機制，LVM是建立在硬盤和分區之上的一個邏輯層，來提高磁盤分區管理的靈活性。LVM是在磁盤分區和文件系統之間添加的一個邏輯層，來為文件系統屏蔽下層磁盤分區布局，提供一個抽象的盤卷，在盤卷上建立文件系統。物理卷（physical volume）物理卷就是指硬盤分區或從邏輯上與磁盤分區具有同樣功能的設備（如RAID），是LVM的基本存儲邏輯塊，但和基本的物理存儲介質（如分區、磁盤等）比較，卻包含有與LVM相關的管理參數。
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優勢：能夠在線擴容當前的分區容量。
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結構：在整個LVM結構當中以此分為：“物理卷、物理卷分區、卷組、邏輯卷”，下面我詳細解釋一下這四種結構：
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物理卷：Physical Volume，簡稱PV，一個物理卷只不過是一個有LVM管理數據添加在里面的物理存儲介質。要使用LVM系統，首先對要用於LVM的磁盤進行初始化，初始化的目的就是將磁盤或分區標識為LVM 的物理卷。使用pvcreate 命令可以將一個磁盤標記為 LVM 物理卷。
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物理分區：Physical Extents，簡稱PE，LVM將每個物理卷分別叫做物理分區的可尋址存儲單元，存儲單元的大小通常為幾MB。磁盤的開頭部分為LVM元數據，之后從索引為零開始，每個物理分區的索引依次遞增一，按順序進行分配。
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卷組：Volume Group，簡稱VG，物理卷可以組織為卷組。卷組可以由一個或多個物理卷組成，同時系統中可以有多個卷組。創建了卷組之后，該卷組（而不是磁盤）便是表示數據存儲的實體。因此，盡管以前是將磁盤從一個系統移動到另一個系統，使用了 LVM 之后，會將卷組從一個系統移動到另一個系統。出於這種原因，通常在一個系統上創建多個卷組會比較方便。
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邏輯分區：Logical Extents，簡稱LE，邏輯卷的基本分配單元稱為邏輯分區。邏輯分區映射到物理分區，因此，如果物理分區的尺寸小為4MB，那么邏輯分區的尺寸也將為4MB。邏輯卷的大小取決於所分配的邏輯分區數量。
生產環境
[root@Nexus3 ~]# cat /etc/redhat-release
CentOS Linux release 7.7.1908 (Core)
[root@Nexus3 ~]# lvm version
LVM version: 2.02.185(2)-RHEL7 (2019-05-13)
Library version: 1.02.158-RHEL7 (2019-05-13)
Driver version: 4.37.1
硬盤擴容20G->100G
[root@Nexus3 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs tmpfs 3.9G 8.8M 3.9G 1% /run
tmpfs tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
-----/dev/mapper/centos-root是我們需要擴的卷-------------------------
/dev/mapper/centos-root xfs 17G 1.2G 16G 7% /
/dev/sda1 xfs 1014M 136M 879M 14% /boot
tmpfs tmpfs 799M 0 799M 0% /run/user/0
查看本地物理硬盤
[root@Nexus3 ~]# fdisk -l
-----磁盤容量100G-------------------------
Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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
Disk label type: dos
Disk identifier: 0x000c35ff
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 41943039 19921920 8e Linux LVM
-----正在使用18.2G，我們需要將此硬盤擴容-------------------------
Disk /dev/mapper/centos-root: 18.2 GB, 18249416704 bytes, 35643392 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
Disk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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
硬盤分區
根據實際情況選擇自己的硬盤
[root@Nexus3 ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
-----列出當前分區-------------------------
Command (m for help): p
Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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
Disk label type: dos
Disk identifier: 0x000c35ff
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
-----注意后面Id System 后面用到-------------------------
/dev/sda2 2099200 41943039 19921920 8e Linux LVM
-----創建分區n，一路回車就會創建sda3全部容量-------------------------
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p):
Using default response p
Partition number (3,4, default 3):
First sector (41943040-209715199, default 41943040):
Using default value 41943040
Last sector, +sectors or +size{K,M,G} (41943040-209715199, default 209715199):
Using default value 209715199
Partition 3 of type Linux and of size 80 GiB is set
-----驗證分區-------------------------
Command (m for help): p
Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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
Disk label type: dos
Disk identifier: 0x000c35ff
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 41943039 19921920 8e Linux LVM
-----看看后面Id System需要修改-------------------------
/dev/sda3 41943040 209715199 83886080 83 Linux
-----修改Id-------------------------
Command (m for help): t
Partition number (1-3, default 3):
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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
Disk label type: dos
Disk identifier: 0x000c35ff
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 41943039 19921920 8e Linux LVM
/dev/sda3 41943040 209715199 83886080 8e Linux LVM
-----保存！！！！！-------------------------
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
-----同步磁盤狀態-------------------------
[root@Nexus3 ~]# partprobe
創建物理卷
- pvcreate <物理分區>
-----查詢當前PV-------------------------
[root@Nexus3 ~]# pvdisplay
--- 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 2MrxDf-dTQK-I7iK-5VUs-bcrv-Af2t-fVaAiL
-----創建新的PV-------------------------
[root@Nexus3 ~]# pvcreate /dev/sda3
Physical volume "/dev/sda3" successfully created.
[root@Nexus3 ~]# pvdisplay
--- 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 2MrxDf-dTQK-I7iK-5VUs-bcrv-Af2t-fVaAiL
-----這個是我們創建的-------------------------
"/dev/sda3" is a new physical volume of "80.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sda3
VG Name
PV Size 80.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID kfO9Yc-ToQb-2vnf-8muc-MNsZ-oxJV-vi1vVe
擴展卷組
- vgextend <卷組VG Name> <物理卷PV Name>
-----查看當前VG-------------------------
[root@Nexus3 ~]# vgdisplay
--- Volume group ---
-----VG Name需要用到-------------------------
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 Wx79ds-a3LO-VhXo-HJdk-fr0X-C9UX-KOqfSK
-----擴展卷組-------------------------
[root@Nexus3 ~]# vgextend centos /dev/sda3
Volume group "centos" successfully extended
邏輯卷擴展
- lvextend -l +100%free </dev/mapper/centos-root> #前面df -hT看到的信息
-----查看邏輯卷-------------------------
[root@Nexus3 ~]# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID bgsynr-YUZE-LX2j-NIgG-sqqU-wVxb-GIZDg7
LV Write Access read/write
LV Creation host, time localhost, 2019-11-22 14:16:37 +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
-----我們需要擴展該卷-------------------------
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID lkRm4c-8g6X-ZWm2-Y86h-aKXs-i2lN-ZKdGaD
LV Write Access read/write
LV Creation host, time localhost, 2019-11-22 14:16:37 +0800
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
-----擴充-------------------------
[root@Nexus3 ~]# lvextend -l +100%free /dev/mapper/centos-root
Size of logical volume centos/root changed from <17.00 GiB (4351 extents) to 96.99 GiB (24830 extents).
Logical volume centos/root successfully resized.
動態格式化擴容磁盤
[root@Nexus3 ~]# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=1113856 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=4455424, 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 4455424 to 25425920
驗證
[root@Nexus3 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs tmpfs 3.9G 8.9M 3.9G 1% /run
tmpfs tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
-----100G-------------------------
/dev/mapper/centos-root xfs 97G 1.2G 96G 2% /
/dev/sda1 xfs 1014M 136M 879M 14% /boot
tmpfs tmpfs 799M 0 799M 0% /run/user/0