lvm讲解
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lvm
lvm (Logical Volume Manager)逻辑分卷管理器；可用于管理磁盘驱动器或其他类似的大容量存储设备.
通过LVM，可以实现存储空间的抽象化并在上面建立虚拟分区（virtual partitions），可以更简便地扩大和缩小分区，可以增删分区时无需担心某个硬盘上没有足够的连续空间，LVM是用来方便管理的，不会提供额外的安全保证。lvm 基本组成
物理卷Physical volume (PV)：可以在上面建立卷组的媒介，可以是硬盘分区，也可以是硬盘本身或者回环文件（loopback file）。物理卷包括一个特殊的header，其余部分被切割为一块块物理区域（physical extents）。
卷组Volume group (VG)：将一组物理卷收集为一个管理单元。
逻辑卷Logical volume (LV)：虚拟分区，由物理区域（physical extents）组成。
物理区域Physical extent (PE)：硬盘可供指派给逻辑卷的最小单位（通常为4MB）示例：
两块物理硬盘
硬盘1 (/dev/sda):
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
|分区1 50GB (物理卷) |分区2 50GB (物理卷) |
|/dev/sda1 |/dev/sda2 |
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _|
硬盘2 (/dev/sdb):
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
|分区1 120GB (物理卷) |
|/dev/sdb1 |
| _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |LVM方式
卷组VG1 (/dev/MyStorage/ = /dev/sda1 + /dev/sda2 + /dev/sdb1):
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
|逻辑卷1 15GB |逻辑卷2 35GB |逻辑卷3 170GB |
|/dev/MyStorage/rootvol |/dev/MyStorage/homevol |/dev/MyStorage/mediavol |
|_ _ _ _ _ _ _ _ _ _ _ _ _ _ __|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |创建LVM
实例：
1、创建分区：
fdisk /dev/sdb2、t 更改ID
Command (m for help): t
Partition number (1-3,5, default 5): 1
Hex code (type L to list all codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx
5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data
6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility
8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt
9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access
a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT
f ‘W95 Ext‘d (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary
16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT
1e Hidden W95 FAT1 80 Old Minix
Hex code (type L to list all codes): 8e
Changed type of partition ‘Linux‘ to ‘Linux LVM‘
Command (m for help): t
Partition number (1-3,5, default 5): 2
Hex code (type L to list all codes): 8e
Changed type of partition ‘Linux‘ to ‘Linux LVM‘ `3、准备物理卷
pvcreate命令用于将物理硬盘分区初始化为物理卷，以便LVM使用
pvcreate /dev/sdb1 /dev/sdb2
在使用pvcreate命令时，如果提示没有这个命令，使用yum安装，在使用yum安装时，可以使用yum provides pvcreate来确认命令的依赖软件包。
[[email protected] ~]# pvcreate /dev/sdb1 /dev/sdb2
WARNING: xfs signature detected on /dev/sdb1 at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/sdb1.
WARNING: xfs signature detected on /dev/sdb2 at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/sdb2.
Physical volume "/dev/sdb1" successfully created.
Physical volume "/dev/sdb2" successfully created.验证物理卷：
[[email protected] ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sdb1 lvm2 --- 10.0g 10.0g
/dev/sdb2 lvm2 --- 5.0g 5.0g
详细显示PV信息
[[email protected] ~]# pvdisplay
"/dev/sdb1" is a new physical volume of "10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID UeQKm2-m02J-wUx-AVs7-B7Oj-31I-gbuua
"/dev/sdb2" is a new physical volume of "5.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb2
VG Name
PV Size 5.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID yt1V3N-SPNr-vylp-ZpDz-Drkb-lkdY-41y1r4、创建卷组
vgcreate命令用于创建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。
用法：
vgcreate 卷组名 对应物理卷创建：
[[email protected] ~]# vgcreate vg1 /dev/sdb1 /dev/sdb2
Volume group "vg1" successfully created
查看：
[[email protected] ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vg1 2 0 0 wz--n- 14.99g 14.99g5、创建逻辑卷
lvcreate 命令用于创建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vg100上创建一个逻辑卷lvol0，则此逻辑卷对应的设备文件为/dev/vg100/lvol0。
常用参数：
-L 指定大小# vg1上创建一个3G的lv
[[email protected] ~]# lvcreate -L 3G -n lv01 vg1
Logical volume "lv01" created.
# vg1上创建占vg1容量50%的lv02
[[email protected] ~]# lvcreate -l 50%VG -n lv02 vg1
Logical volume "lv02" created.
# 剩余空间全部分配给lv03
[[email protected] ~]# lvcreate -l 100%FREE -n lv03 vg1
Logical volume "lv03" created.
# 检查lv状态
[[email protected] ~]# lvscan
ACTIVE ‘/dev/vg1/lv01‘ [3.00 GiB] inherit
ACTIVE ‘/dev/vg1/lv02‘ [7.50 GiB] inherit
ACTIVE ‘/dev/vg1/lv03‘ [4.50 GiB] inherit6、格式化
[[email protected] ~]# mke2fs -t ext4 /dev/vg1/lv01
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe blocks
196608 inodes, 786432 blocks
39321 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=805306368
24 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912
Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done7、挂载
[[email protected] ~]# mount /dev/vg1/lv01 /date1
[[email protected] ~]# mount /dev/vg1/lv02 /date2
[[email protected] ~]# mount /dev/vg1/lv03 /date3
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 16G 1.9G 14G 12% /
devtmpfs 1.4G 0 1.4G 0% /dev
tmpfs 1.4G 0 1.4G 0% /dev/shm
tmpfs 1.4G 8.6M 1.4G 1% /run
tmpfs 1.4G 0 1.4G 0% /sys/fs/cgroup
/dev/sda1 197M 109M 88M 56% /boot
tmpfs 280M 0 280M 0% /run/user/0
/dev/mapper/vg1-lv01 2.9G 9.0M 2.8G 1% /date1
/dev/mapper/vg1-lv02 7.3G 34M 6.9G 1% /date2
/dev/mapper/vg1-lv03 4.4G 18M 4.1G 1% /date38、写开机启动挂载
编辑 /etc/fstab 文件扩容逻辑卷
lvresize命令用于调整LVM逻辑卷的空间大小，可以增大空间和缩小空间。使用lvresize命令调整逻辑卷空间大小和缩小空间时需要谨慎，因为它有可能导致数据丢失。添加物理卷扩大卷组：
vgextend命令用于动态扩展LVM卷组，它通过向卷组中添加物理卷来增加卷组的容量。LVM卷组中的物理卷可以在使用vgcreate命令创建卷组时添加，也可以使用vgextend命令动态的添加[[email protected] ~]# vgextend vg1 /dev/sdb5
WARNING: ext4 signature detected on /dev/sdb5 at offset 1080. Wipe it? [y/n]: y
Wiping ext4 signature on /dev/sdb5.
Physical volume "/dev/sdb5" successfully created.
Volume group "vg1" successfully extended如果原有vg卷上还有多余空间，则不需要前面的这一步，可以直接用以下步骤扩容：
# 指定容量扩展空间
[[email protected] ~]# lvextend -L +500M /dev/vg1/lv01
Size of logical volume vg1/lv01 changed from 3.00 GiB (768 extents) to 3.49 GiB (893 extents).
Logical volume vg1/lv01 successfully resized.
# 扩展剩余所有空间
[[email protected] ~]# lvextend -l +100%FREE /dev/vg1/lv03
Size of logical volume vg1/lv03 changed from 4.50 GiB (1151 extents) to 9.00 GiB (2305 extents).
Logical volume vg1/lv03 successfully resized.
# 查看状态
[[email protected] ~]# lvscan
ACTIVE ‘/dev/vg1/lv01‘ [3.49 GiB] inherit
ACTIVE ‘/dev/vg1/lv02‘ [7.50 GiB] inherit
ACTIVE ‘/dev/vg1/lv03‘ [9.00 GiB] inherit检查磁盘错误：
在做此操作前，确认磁盘不是挂载状态！！！xfs不需要
[[email protected] ~]# e2fsck -f /dev/vg1/lv01
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg1/lv01: 14/196608 files (0.0% non-contiguous), 31038/786432 blocks更新逻辑卷信息：
如果不更新卷信息，重新挂载后无法识别扩容后的大小！！
[[email protected] ~]# resize2fs /dev/vg1/lv01
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg1/lv01 to 914432 (4k) blocks.
The filesystem on /dev/vg1/lv01 is now 914432 blocks long.
xfs文件系统需要执行：
xfs_growfs /dev/vg1/lv01扩容前大小：
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 16G 1.9G 14G 12% /
devtmpfs 1.4G 0 1.4G 0% /dev
tmpfs 1.4G 0 1.4G 0% /dev/shm
tmpfs 1.4G 8.6M 1.4G 1% /run
tmpfs 1.4G 0 1.4G 0% /sys/fs/cgroup
/dev/sda1 197M 109M 88M 56% /boot
tmpfs 280M 0 280M 0% /run/user/0
/dev/mapper/vg1-lv01 2.9G 9.0M 2.8G 1% /date1
/dev/mapper/vg1-lv02 7.3G 34M 6.9G 1% /date2
/dev/mapper/vg1-lv03 4.4G 18M 4.1G 1% /date3扩容后大小：
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 16G 1.9G 14G 12% /
devtmpfs 1.4G 0 1.4G 0% /dev
tmpfs 1.4G 0 1.4G 0% /dev/shm
tmpfs 1.4G 8.6M 1.4G 1% /run
tmpfs 1.4G 0 1.4G 0% /sys/fs/cgroup
/dev/sda1 197M 109M 88M 56% /boot
tmpfs 280M 0 280M 0% /run/user/0
/dev/mapper/vg1-lv03 8.8G 21M 8.3G 1% /date3
/dev/mapper/vg1-lv02 7.3G 34M 6.9G 1% /date2
/dev/mapper/vg1-lv01 3.4G 12M 3.2G 1% /date1缩减逻辑卷（xfs文件系统不支持）
1、先取消挂载
2、检查磁盘错误：
[[email protected] ~]# e2fsck -f /dev/vg1/lv01
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg1/lv01: 14/196608 files (0.0% non-contiguous), 31038/786432 blocks3、更新逻辑卷信息：
[[email protected] ~]# resize2fs /dev/vg1/lv01 3G
** 后面的这个大小是缩减后的大小**
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vg1/lv01 to 914432 (4k) blocks.
The filesystem on /dev/vg1/lv01 is now 914432 blocks long.4、重设大小：
[[email protected] ~]# lvresize -L 3G /dev/vg1/lv01
WARNING: Reducing active logical volume to 3.00 GiB.
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce vg1/lv01? [y/n]: y
Size of logical volume vg1/lv01 changed from 3.49 GiB (893 extents) to 3.00 GiB (768 extents).
Logical volume vg1/lv01 successfully resized.[[email protected] ~]# lvextend -L 3G /dev/vg1/lv02
New size given (768 extents) not larger than existing size (1919 extents)
[[email protected] ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
lv01 vg1 -wi-ao---- 3.00g
lv02 vg1 -wi-a----- 7.50g
lv03 vg1 -wi-ao---- 9.00g
[[email protected] ~]# mount /dev/vg1/lv02 /date2
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 16G 1.9G 14G 12% /
devtmpfs 1.4G 0 1.4G 0% /dev
tmpfs 1.4G 0 1.4G 0% /dev/shm
tmpfs 1.4G 8.6M 1.4G 1% /run
tmpfs 1.4G 0 1.4G 0% /sys/fs/cgroup
/dev/sda1 197M 109M 88M 56% /boot
tmpfs 280M 0 280M 0% /run/user/0
/dev/mapper/vg1-lv01 2.9G 9.1M 2.8G 1% /date1
/dev/mapper/vg1-lv03 3.9G 18M 3.6G 1% /date3
/dev/mapper/vg1-lv02 2.9G 23M 2.7G 1% /date2lvresize和lvextend 是一样的效果，不过后者要在磁盘挂载后才能看到磁盘大小的变化！！
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