Linux系统磁盘空间扩展指南
Linux系统磁盘空间扩展指南
在云平台或虚拟化环境中，当系统磁盘容量不足时，需要进行磁盘扩容操作。本文详细介绍在Linux系统中通过LVM（逻辑卷管理器）扩展磁盘空间的具体步骤。
一、磁盘分区操作
在控制台完成磁盘添加后，重启系统使新磁盘识别，然后执行以下分区操作。
1.1 创建新分区
使用fdisk工具对磁盘进行分区：
[root@linuxserver ~]# fdisk /dev/sdb
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.
Command (m for help): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
g create a new empty GPT partition table
G create an IRIX (SGI) partition table
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): n
Partition type:
p primary (3 primary, 0 extended, 1 free)
e extended
Select (default e): p
Selected partition 4
First sector (41943040-83886079, default 41943040):
Using default value 41943040
Last sector, +sectors or +size{K,M,G} (41943040-83886079, default 83886079):
Using default value 83886079
Partition 4 of type Linux and of size 20 GiB is set
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.
1.2 查看分区信息
执行以下命令查看当前磁盘分区情况：
[root@linuxserver ~]# fdisk -l
Disk /dev/sdb: 42.9 GB, 42949672960 bytes, 83886080 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: 0x000a9a6f
Device Boot Start End Blocks Id System
/dev/sdb1 2048 6143 2048 83 Linux
/dev/sdb2 * 6144 2103295 1048576 83 Linux
/dev/sdb3 2103296 41943039 19919872 8e Linux LVM
/dev/sdb4 41943040 83886079 20971520 83 Linux
Disk /dev/mapper/centos-root: 19.3 GB, 19323158528 bytes, 37740544 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: 1073 MB, 1073741824 bytes, 2097152 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
1.3 修改分区类型
新创建的分区默认类型为Linux（83），需要将其改为Linux LVM（8e）以便LVM使用：
[root@linuxserver ~]# fdisk /dev/sdb
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.
Command (m for help): t
Partition number (1-4, default 4):
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): 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.
</code>验证分区类型已修改：
[root@linuxserver ~]# fdisk -l
Disk /dev/sdb: 42.9 GB, 42949672960 bytes, 83886080 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: 0x000a9a6f
Device Boot Start End Blocks Id System
/dev/sdb1 2048 6143 2048 83 Linux
/dev/sdb2 * 6144 2103295 1048576 83 Linux
/dev/sdb3 2103296 41943039 19919872 8e Linux LVM
/dev/sdb4 41943040 83886079 20971520 8e Linux LVM
二、LVM卷组扩容
系统重启后，开始进行LVM卷组的扩容操作。
2.1 查看当前卷组状态
[root@linuxserver ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root centos -wi-ao---- <18.00g
swap centos -wi-ao---- 1.00g
[root@linuxserver ~]# 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 gp2KXC-VUTG-0C01-aAed-31UC-HkVO-qi3gus
2.2 创建物理卷
将新分区创建为物理卷：
[root@linuxserver ~]# pvcreate /dev/sdb4
Physical volume "/dev/sdb4" successfully created.
注意：如果遇到"Device /dev/sdb4 not found"错误，需要执行partprobe命令刷新分区表：
[root@linuxserver ~]# partprobe
Warning: 无法以读写方式打开 /dev/sr0 (只读文件系统)。/dev/sr0 已按照只读方式打开。
[root@linuxserver ~]# pvcreate /dev/sdb4
Physical volume "/dev/sdb4" successfully created.
2.3 扩展卷组
[root@linuxserver ~]# vgextend centos /dev/sdb4
Volume group "centos" successfully extended
[root@linuxserver ~]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
VG Size 38.99 GiB
PE Size 4.00 MiB
Total PE 9982
Alloc PE / Size 4863 / <19.00 GiB
Free PE / Size 5119 / <20.00 GiB
VG UUID gp2KXC-VUTG-0C01-aAed-31UC-HkVO-qi3gus
2.4 扩展逻辑卷
[root@linuxserver ~]# lvextend -l +100%FREE /dev/centos/root /dev/sdb4
Size of logical volume centos/root changed from <18.00 GiB (4607 extents) to <36.50 GiB (9343 extents).
Logical volume centos/root successfully resized.
三、文件系统扩容
3.1 查看文件系统类型
[root@linuxserver ~]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 37G 14G 24G 37% /
devtmpfs devtmpfs 898M 0 898M 0% /dev
tmpfs tmpfs 910M 0 910M 0% /dev/shm
tmpfs tmpfs 910M 9.6M 901M 2% /run
tmpfs tmpfs 910M 0 910M 0% /sys/fs/cgroup
/dev/sdb2 xfs 1014M 148M 867M 15% /boot
tmpfs tmpfs 182M 0 182M 0% /run/user/0
3.2 调整文件系统大小
根据文件系统类型选择对应的扩容命令。当前系统使用XFS文件系统：
[root@linuxserver ~]# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=1179392 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=4717568, 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 4717568 to 9567232
补充说明：如果系统使用的是ext4文件系统，应使用resize2fs命令进行扩容：
[root@linuxserver ~]# resize2fs /dev/mapper/centos-root
至此，磁盘扩容操作全部完成。
