在Linux学习过程中，可能会遇到根目录存储空间不足的问题，这时候如果只是新增一块硬盘并挂载到某个目录上，还需要将数据转移至新的硬盘中才能缓解存储压力。这种操作未免有些繁琐，那可不可以直接对跟目录进行扩容呢？当然是可以的，接下来就给大家介绍操作步骤：
实验环境：RHEL7系统（默认已部署LVM）、VMware Workstation 12虚拟软件
第1步：给虚拟机新增一块20GB的硬盘
第2步：查看系统盘的分区类型，最后记得输入q不保存退出
[root@linuxprobe ~]# 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.
Command (m for help): p //输入p查看分区信息
Disk /dev/sda: 21.5 GB, 21474836480 bytes, 41943040 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: 0x00091636
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 41943039 20458496 8e Linux LVM //分区类型为Linux LVM
Command (m for help): q //输入q不保存退出
第3步：对新硬盘进行分区，并设置分区类型
[root@linuxprobe ~]# 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): n //添加一个新分区
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p //主分区
Partition number (1-4, default 1): 1 //分区编号为1
First sector (2048-41943039, default 2048): <此处按下回车键>
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +10G //分区大小为10GB
Partition 1 of type Linux and of size 10 GiB is set
Command (m for help): p //再次查看分区信息
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x1894a517
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20973567 10485760 83 Linux //新的分区添加成功，不过分区类型不对
Command (m for help): t //变更分区的类型
Selected partition 1
Hex code (type L to list all codes): 8e //输入8e即"Linux LVM"
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p //再次查看分区信息
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x1894a517
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20973567 10485760 8e Linux LVM //分区类型变更成功，与系统分区一致
Command (m for help): w //最后记得要保存退出
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
第4步：让新添加的硬盘分区支持LVM技术
[root@linuxprobe ~]# pvcreate /dev/sdb1
Physical volume "/dev/sdb1" successfully created
第5步：查看当前系统的卷组，并将/dev/sdb1硬盘分区加入到卷组中
[root@linuxprobe ~]# vgdisplay
--- Volume group ---
VG Name rhel //卷组名为"rhel"
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 19.51 GiB //卷组的总容量大小
PE Size 4.00 MiB
Total PE 4994
Alloc PE / Size 4994 / 19.51 GiB
Free PE / Size 0 / 0
VG UUID mGomiV-U0sF-wKii-YxOh-V7Gw-VEQ4-yIkcRD
[root@linuxprobe ~]# vgextend rhel /dev/sdb1 //把/dev/sdb1硬盘分区加入到rhel卷组中
Volume group "rhel" successfully extended
[root@linuxprobe ~]# vgdisplay
--- Volume group ---
VG Name rhel
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 29.50 GiB //卷组的容量增大了10GB
PE Size 4.00 MiB
Total PE 7553
Alloc PE / Size 4994 / 19.51 GiB
Free PE / Size 2559 / 10.00 GiB
VG UUID mGomiV-U0sF-wKii-YxOh-V7Gw-VEQ4-yIkcRD
第6步：查看当前逻辑卷信息
[root@linuxprobe ~]# lvdisplay
--- Logical volume ---
LV Path /dev/rhel/swap //用来充当SWAP分区，我们这里不管它
LV Name swap
VG Name rhel
LV UUID d2gNWI-6Oin-9Q3r-OGLp-0nf5-0Dun-Z8EvgS
LV Write Access read/write
LV Creation host, time localhost, 2020-02-15 20:19:35 +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 256
Block device 253:1
--- Logical volume ---
LV Path /dev/rhel/root //该逻辑卷实际就是Linux系统盘，我们将对它进行扩容
LV Name root //逻辑卷名为root
VG Name rhel
LV UUID rI6Xvu-eCJx-0WFO-TuUj-LQWM-WuUc-3uE6zc
LV Write Access read/write
LV Creation host, time localhost, 2020-02-15 20:19:35 +0800
LV Status available
# open 1
LV Size 17.51 GiB //逻辑卷的大小，即系统盘大小
Current LE 4482
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
第7步：对root逻辑卷进行扩容操作
[root@linuxprobe ~]# lvextend -L +10G /dev/rhel/root
Extending logical volume root to 27.51 GiB
Insufficient free space: 2560 extents needed, but only 2559 available //显示实际空闲容量不足10GB，比10GB稍微小一点点
[root@linuxprobe ~]# lvextend -L +5G /dev/rhel/root //这里我们先扩容5GB
Extending logical volume root to 22.51 GiB
Logical volume root successfully resized
[root@linuxprobe ~]# lvdisplay
----------------省略部分输出内容------------------------
--- Logical volume ---
LV Path /dev/rhel/root
LV Name root
VG Name rhel
LV UUID rI6Xvu-eCJx-0WFO-TuUj-LQWM-WuUc-3uE6zc
LV Write Access read/write
LV Creation host, time localhost, 2020-02-15 20:19:35 +0800
LV Status available
# open 1
LV Size 22.51 GiB //容量已从17.51GB提升至22.51GB
Current LE 5762
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
第8步：重置root逻辑卷的大小。xfs系统不需要先umount操作
[root@linuxprobe ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 18G 3.1G 15G 18% / //重置之前，先查看当前系统盘的大小，此时显示为18GB
devtmpfs 985M 0 985M 0% /dev
tmpfs 994M 80K 994M 1% /dev/shm
tmpfs 994M 8.9M 986M 1% /run
tmpfs 994M 0 994M 0% /sys/fs/cgroup
/dev/sr0 3.5G 3.5G 0 100% /media/cdrom
/dev/sda1 497M 119M 379M 24% /boot
[root@linuxprobe ~]# xfs_growfs /dev/rhel/root //重置root逻辑卷大小
meta-data=/dev/mapper/rhel-root isize=256 agcount=4, agsize=1147392 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=4589568, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
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 4589568 to 5900288
[root@linuxprobe ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 23G 3.1G 20G 14% / //系统盘成功扩容至23G，增加了5GB容量，且重启依然生效
devtmpfs 985M 0 985M 0% /dev
tmpfs 994M 80K 994M 1% /dev/shm
tmpfs 994M 8.9M 986M 1% /run
tmpfs 994M 0 994M 0% /sys/fs/cgroup
/dev/sr0 3.5G 3.5G 0 100% /media/cdrom
/dev/sda1 497M 119M 379M 24% /boot
至此，Linux系统盘扩容操作完毕。
知识补充：
1、重置逻辑卷命令 "xfs_growfs /dev/rhel/root" 和 "xfs_growfs /dev/mapper/rhel-root" 效果一样；
2、如果是ext4文件系统，重置命令为"resize2fs /dev/rhel/root"；
3、xfs文件系统只能扩容，不允许缩容。
[root@linuxprobe ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 rhel lvm2 a-- 19.51g 0
/dev/sdb1 rhel lvm2 a-- 10.00g 5.00g //还省5GB空闲容量