Linux - 挂载磁盘 + 通过LVM动态实现磁盘的动态扩容
1 LVM是什么
1.1 概念解释
LVM(Logical Volume Manager), 逻辑卷管理, 是一种将一至多个硬盘的分区在逻辑上进行组合, 当成一个大硬盘来使用.

当硬盘空间不足时, 可以动态地添加其它硬盘的分区到已有的卷组中 —— 磁盘空间的动态管理.

1.2 为什么用LVM
LVM通常用于装备大量磁盘的系统, 比如服务器中的磁盘阵列.

但LVM同样适用于仅有一、两块硬盘的小系统.

1.2.1 不使用LVM时的扩容思路
传统的文件系统是基于分区的, 一个文件系统对应一个分区, 这种方式比较直观, 但不易改变:

(1) 不同的分区相互独立, 单独的文件不能跨分区存储, 容易出现硬盘的利用率不均衡;

(2) 当一个文件系统/分区装满时, 是不能对其进行扩容的, 只能采用重新分区/建立文件系统, 重新分区会丢失数据, 就要:

① 做数据的迁移和备份;
② 或者把分区中的数据移到另一个更大的分区中;
③ 或者采用符号连接的方式使用其它分区的空间 —— 都非常麻烦;

(3) 如果要把硬盘上的多个分区合并在一起使用, 只能采用重新分区的方式, —— 需要做好数据的备份与恢复.

1.2.2 使用LVM时的扩容思路
使用LVM时技术时, 情况有所不同:

(1) 硬盘的多个分区由LVM统一管理为卷组, 可以很轻松地加入或移走某个分区 —— 也就是扩大或减小卷组的可用容量, 充分利用硬盘空间;

(2) 文件系统建立在逻辑卷上, 而逻辑卷可以根据需要改变大小(在卷组容量范围内)以满足要求;

(3) 文件系统建立在LVM上, 可以跨分区存储访问, 更加方便;

强烈建议对拥有多个磁盘的系统, 使用LVM管理磁盘.

1.3 名词解释
PV(Physical Volume): 物理卷, 处于LVM最底层, 可以是物理硬盘或者分区;

PP(Physical Extend): 物理区域, PV中可以用于分配的最小存储单元, 可以在创建PV的时候指定, 如1M, 2M, 4M, 8M…..组成同一VG中所有PV的PE大小应该相同;

VG(Volume Group): 卷组, 建立在PV之上, 可以含有一个到多个PV;

LV(Logical Volume): 逻辑卷, 建立在VG之上, 相当于原来分区的概念, 不过大小可以动态改变.

2 普通的挂载磁盘方法
2.1 创建分区的主要操作
(1) 查看分区情况 - fdisk -l

[root@localhost ~]# fdisk -l

Disk /dev/sda: 299.0 GB, 298999349248 bytes # 磁盘/dev/sda
255 heads, 63 sectors/track, 36351 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x4d69fe0e

Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux # 分为2个区, sda1
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 36352 291785728 8e Linux LVM # sda2

磁盘/dev/sdb没有分区

Disk /dev/sdb: 4000.0 GB, 3999999721472 bytes
255 heads, 63 sectors/track, 486305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

......
(2) 查看已有磁盘 - lsblk

[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 278.5G 0 disk
├─sda1 8:1 0 200M 0 part /boot
└─sda2 8:2 0 278.3G 0 part
└─VolGroup-LogVol (dm-0) 253:0 0 1.9T 0 lvm / # LVM类型的分区
sdb 8:32 0 3.7T 0 disk # 还没有分区的新磁盘
(3) 对新磁盘进行分区 - fdisk /dev/sdb

[root@localhost ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xf91f8c4c.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: The size of this disk is 4.0 TB (4000225165312 bytes).
DOS partition table format can not be used on drives for volumes
larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID
partition table format (GPT).

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to

     switch off the mode (command 'c') and change display units to
     sectors (command 'u').

Command (m for help): n # n 表示新建分区
Command action
e extended
p primary partition (1-4)
p # p 表示分区类型为主分区, 主分区只有1-4种选择
Partition number (1-4): 1 # 主分区的编号
First cylinder (1-486333, default 1): # 开始扇区号, 直接回车, 使用默认值1
Using default value 1

结束扇区号, 使用默认值 --- 这里只加载了新磁盘的一半(2T), 所以还需要再次创建分区/dev/sdb2使用剩下的一半.

Last cylinder, +cylinders or +size{K,M,G} (1-267349, default 267349):
Using default value 267349

Command (m for help): w # 将上述设置写入分区表并退出
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
(4) 再次查看分区情况 - fdisk -l

多出来一个/dev/sdb1的区, 这个1就是之前主分区之后指定的分区编号.

[root@localhost ~]# fdisk -l

Disk /dev/sda: 299.0 GB, 298999349248 bytes
255 heads, 63 sectors/track, 36351 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x4d69fe0e

Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 36352 291785728 8e Linux LVM

/dev/sdb磁盘:

多出来的分区/dev/sdb1

Device Boot Start End Blocks Id System
/dev/sdb1 1 267349 2147480811 83 Linux

......
(5) 查看当前分区表中的分区信息 - cat /proc/partitions

[root@localhost ~]# cat /proc/partitions
major minor #blocks name

8 0 291991552 sda
8 1 204800 sda1
8 2 291785728 sda2
8 32 3906249728 sdb # 添加的新磁盘
8 33 2147480811 sdb1 # 创建的新分区
253 0 2046660608 dm-0
如果创建完之后，cat /proc/partitions 查看不到对应的分区, 使用 parprobe 刷新命令即可:

[root@localhost ~]# partprobe /dev/sdc
2.2 格式化新分区
(1) 格式化新分区 - mkfs -t

这里建议将新分区格式化为ext4文件类型, 还有ext2, ext3等文件类型, 区别请参考博客 ext2、ext3与ext4的区别 .

[root@localhost ~]# mkfs -t ext4 /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
134217728 inodes, 536870202 blocks
26843510 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
16384 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:

    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
    4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
    102400000, 214990848, 512000000

Writing inode tables: 8874/16384
(2) 等待一小会后, 将出现下述提示, 说明格式化完成:

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
2.3 挂载新分区
(1) 创建目录, 并将 /dev/sdb1挂在到该目录下:

[root@localhost /]# mkdir data && cd /data
[root@localhost data]# mount /dev/sdc1 /data1
(2) 查看挂载是否成功:

[root@localhost data]# df -l
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/VolGroup-LogVol 286901696 18601728 253726196 7% /
tmpfs 66020980 0 66020980 0% /dev/shm
/dev/sda1 495844 33476 436768 8% /boot

挂载成功:

/dev/sdb1 2113784984 202776 2006208168 1% /data
2.4 设置开机自动挂载
编辑文件 /etc/fstab:

[root@localhost data]# vim /etc/fstab

文件内容如下:

/etc/fstab

Created by anaconda on Wed Sep 12 10:41:40 2018

Accessible filesystems, by reference, are maintained under '/dev/disk'

See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

/dev/mapper/VolGroup-LogVol / ext4 defaults 1 1
/dev/sdb1 /data ext4 defaults 1 1
UUID=22b1d425-d050-43c3-a735-06d48bbb9051 /boot ext4 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
3 LVM方式挂载磁盘 - 推荐
3.1 查看磁盘容量信息
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VG-LogVol 1.9T 1.8T 61G 97% / # LVM卷组-逻辑卷
tmpfs 63G 0 63G 0% /dev/shm
/dev/sda1 485M 40M 421M 9% /boot
3.2 查看磁盘扇区信息
[root@localhost ~]# fdisk -l

Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux # 分为2个区, sda1
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 36352 291785728 8e Linux LVM # LVM类型的sda2

新添加的磁盘/dev/sdb, 没有分区

LVM格式的卷组信息:

Disk /dev/mapper/VolGroup-LogVol: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
3.3 创建分区
[root@localhost ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x5b3d66ba.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: The size of this disk is 4.0 TB (3999999721472 bytes).
DOS partition table format can not be used on drives for volumes
larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID
partition table format (GPT).

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to

     switch off the mode (command 'c') and change display units to
     sectors (command 'u').

Command (m for help): n # 添加分区
Command action
e extended
p primary partition (1-4)
p # 添加主分区
Partition number (1-4): 1 # 1号主分区, 即/dev/sdb1
First cylinder (1-486305, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-267349, default 267349): 486305
Value out of range.
Last cylinder, +cylinders or +size{K,M,G} (1-267349, default 267349):
Using default value 267349

Command (m for help): n # 继续添加分区
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2 # 2号主分区, 即/dev/sdc2
First cylinder (267350-486305, default 267350):
Using default value 267350
Last cylinder, +cylinders or +size{K,M,G} (267350-486305, default 486305):
Using default value 486305

Command (m for help): p # 打印分区信息:

Device Boot Start End Blocks Id System
/dev/sdb1 1 267349 2147480811 83 Linux
/dev/sdb2 267350 486305 1758764070 83 Linux

Command (m for help): t # 转换类型
Partition number (1-4): 1
Partition number (1-4): 1 # 修改/dev/sdb1为Linux LVM类型:
Hex code (type L to list codes): L # 查看可用类型:

0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): 8e # 修改为8e, 即Linux LVM类型
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): t
Partition number (1-4): 2 # 修改/dev/sdc2为Linux LVM类型
Hex code (type L to list codes): 8e
Changed system type of partition 2 to 8e (Linux LVM)

Command (m for help): p # 再次查看相关信息:

Disk /dev/sdc: 4000.0 GB, 3999999721472 bytes
255 heads, 63 sectors/track, 486305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x5b3d66ba

Device Boot Start End Blocks Id System
/dev/sdb1 1 267349 2147480811 8e Linux LVM # Id已改变
/dev/sdb2 267350 486305 1758764070 8e Linux LVM

Command (m for help): w # 保存并退出
The partition table has been altered! # 修改成功

Calling ioctl() to re-read partition table.
Syncing disks.
3.4 创建物理卷
[root@localhost ~]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created
[root@localhost ~]# pvcreate /dev/sdb2
Physical volume "/dev/sdb2" successfully created
3.5 扩展卷组

查看已有卷组, 发现该卷组就是需要扩容的卷组, 就不必再次创建卷组, 而是直接扩展卷组即可:

[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup 2 2 0 wz--n- 1.91t 0

扩展卷组:

[root@localhost ~]# vgextend VolGroup /dev/sdb1
Volume group "VolGroup" successfully extended
[root@localhost ~]# vgextend VolGroup /dev/sdb2
Volume group "VolGroup" successfully extended
说明: 如果出现下述无法挂载物理磁盘到卷组中的信息, 说明这块物理磁盘已经挂载了, 需要先卸载, 然后再执行创建分区+卷组的操作:

[root@localhost /]# vgextend VolGroup /dev/sdb1
No physical volume label read from /dev/sdb1
Physical volume /dev/sdb1 not found
Can't open /dev/sdb1 exclusively. Mounted filesystem?
Unable to add physical volume '/dev/sdb1' to volume group 'VolGroup'.
3.6 扩展逻辑卷

扩展逻辑卷, 即扩容:

[root@localhost ~]# lvextend -l +100%FREE /dev/mapper/VolGroup-LogVol
Extending logical volume lv_root to 5.54 TiB
Logical volume lv_root successfully resized

上述命令是将所有的空闲空间都扩容到逻辑卷中, 也可指定扩容的大小:

lvextend -l +100G /dev/mapper/VolGroup-LogVol
3.7 查看磁盘卷组信息
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 278.5G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 278G 0 part
├─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm /
sdb 8:16 0 1.6T 0 disk
└─sdb1 8:17 0 1.6T 0 part
└─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm /
sdc 8:32 0 3.7T 0 disk
├─sdc1 8:33 0 2T 0 part
│ └─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm /
└─sdc2 8:34 0 1.7T 0 part
└─VolGroup-LogVol (dm-0) 253:0 0 5.6T 0 lvm /
3.8 调整文件系统的大小

CentOS 7重新读取磁盘大小:

[root@localhost ~]# xfs_growfs /dev/mapper/VolGroup-LogVol
xfs_growfs: /dev/mapper/VolGroup-LogVol is not a mounted XFS filesystem

CentOS 6.5重新读取磁盘大小:

ext4格式, resize2fs会遍历整个磁盘, 速度比较慢, 但是不影响读写数据, 可以令其在后台运行.

[root@localhost ~]# resize2fs /dev/mapper/VolGroup-LogVol
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup-LogVol is mounted on /; on-line resizing required
old desc_blocks = 122, new_desc_blocks = 355
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 1487098880 (4k) blocks.

等了差不多20分钟, 出来了下面这货:

The filesystem on /dev/mapper/VolGroup-LogVol is now 1487098880 blocks long.

赶紧看下扩容成果吧:

[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-LogVol 5.5T 1.8T 3.5T 34% / # 扩容成功
tmpfs 63G 0 63G 0% /dev/shm
/dev/sda1 485M 40M 421M 9% /boot
3.9 附录 - 创建卷组
对应 [3.5] 节的扩展卷组, 如果卷组不存在, 则需要创建之. 下述VolGroup是卷组名称.

vgcreate VolGroup /dev/sdb1

创建逻辑卷, 名称为: mylv. (操作系统中将产生: /dev/VolGroup/mylv目录)

将当前卷组中的100G空间分配到逻辑卷中

lvcreate -L 100G VolGroup -n mylv

或将当前卷组中的所有空闲空间全都分配到逻辑卷中:

lvcreate -l +100%FREE VolGroup -n mylv

格式化逻辑卷组:

mkfs -t ext4 /dev/VolGroup/mylv

挂载卷组到指定目录下, 如果是挂载到根目录, 则无需向/etc/fstab文件中添加启动项.

mount -t ext4 /dev/VolGroup/mylv /data
参考资料
Linux的LVM详解

ext2、ext3与ext4的区别

Linux 下挂载硬盘的方法

linux磁盘管理、新增磁盘、分区、挂载

版权声明
作者: ma_shoufeng(马瘦风)

出处: 博客园马瘦风的博客

Linux - 挂载磁盘 + 通过LVM动态实现磁盘的动态扩容