參考轉載地址：https://segmentfault.com/a/1190000007645451 (親測有效)
VirtualBox中安裝了CentOS 7，給同事用來做kafka和zookeeper測試服務器。昨晚kafka意外終止，看了日誌發現是/root只分配了1GiB大小，已接近飽和。開始bing，總結一下步驟：
列出各分區使用情況：
# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 997M 994M 2.9M 100% /
devtmpfs devtmpfs 915M 0 915M 0% /dev
tmpfs tmpfs 921M 0 921M 0% /dev/shm
tmpfs tmpfs 921M 17M 905M 2% /run
tmpfs tmpfs 921M 0 921M 0% /sys/fs/cgroup
/dev/mapper/centos-usr xfs 4.9G 1.6G 3.4G 33% /usr
/dev/sda1 xfs 97M 66M 31M 69% /boot
/dev/mapper/centos-var xfs 2.4G 473M 1.9G 21% /var
可以看見 /dev/mapper/centos-root 已經使用了100%，我們準備爲它擴容。
在VirtualBox中添加一塊新的虛擬磁盤：
先關閉操作系統。在VirtualBox中選中當前VM，設置->存儲->控制器->SATA控制器，點擊圖標“添加虛擬硬盤”，新建一個虛擬硬盤。我增加了一塊3GiB大小的虛擬磁盤，保存後再次啓動虛擬機。
創建新分區
先看一下現有磁盤情況：
# fdisk -l
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: 0x000940ec
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 83 Linux
/dev/sda2 206848 41943039 20868096 8e Linux LVM
Disk /dev/sdb: 3221 MB, 3221225472 bytes, 6291456 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: 2097 MB, 2097152000 bytes, 4096000 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-usr: 5242 MB, 5242880000 bytes, 10240000 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-root: 1048 MB, 1048576000 bytes, 2048000 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
...
已經可以看到新磁盤/dev/sdb。
對新磁盤進行分區
# fdisk /dev/sdb
在fdisk的交互模式中，依次輸入：
n //創建新分區
p //創建主分區
<回車> //默認分區編號
<回車> //默認起始扇區位置。
<回車> //默認結束扇區位置。
w //寫入分區表
這樣就把整個磁盤分成了一個區。
再看一下現有磁盤情況
# partprobe //強制內核讀取磁盤分區表，不然下面命令將不能顯示出新的分區
# fdisk -l
Device Boot Start End Blocks Id System
/dev/sdb1 2048 6291455 3144704 83 Linux
將新分區用於擴展/root
先看一下卷分組：
# vgdisplay -v
Finding all volume groups
Finding volume group "centos"
--- Volume group ---
VG Name centos //記錄下卷分組名，以待後用
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 6
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 5
Open LV 5
Max PV 0
Cur PV 1
Act PV 1
VG Size 19.90 GiB
PE Size 4.00 MiB
Total PE 5094
Alloc PE / Size 5093 / 19.89 GiB
Free PE / Size 1 / 4.00 MiB
VG UUID vtJL08-7Jxi-5IqK-3fUg-Pben-682a-wiv2GL
--- Logical volume ---
LV Path /dev/centos/root //待擴展的分區，記錄待用
LV Name root
VG Name centos
LV UUID ZWTgoT-AMWs-g54v-dZA1-NQUj-mqGa-8tmr4U
LV Write Access read/write
LV Creation host, time localhost, 2016-07-03 21:59:31 -0400
LV Status available
# open 1
LV Size 1000.00 MiB
Current LE 250
Segments 1
Allocation inherit
Read ahead sectors auto
currently set to 256
Block device 253:2
...
--- Physical volumes ---
PV Name /dev/sda2
PV UUID fiVH1e-lwfi-63Lr-oIlK-GDZI-dcuZ-T04VlC
PV Status allocatable
Total PE / Free PE 5094 / 1
...
爲之前新增的分區創建物理卷
# pvcreate /dev/sdb1
查看結果：
# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name centos
PV Size 19.90 GiB / not usable 3.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 5094
Free PE 1
Allocated PE 5093
PV UUID fiVH1e-lwfi-63Lr-oIlK-GDZI-dcuZ-T04VlC
"/dev/sdb1" is a new physical volume of "3.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sdb1
VG Name
PV Size 3.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID VGXSAn-UiZ0-Fy40-eQxb-53xA-5hZM-3eGPg0
擴展卷分組,"centos"是vgdisplay命令查到的卷分組名
# vgextend centos /dev/sdb1
查看擴展結果，可用下面命令：
# lvdisplay
下面擴展邏輯卷/dev/centos/root
# lvextend -L +3G /dev/centos/root
再運行下面命令將文件系統擴大：
# xfs_growfs /dev/centos/root
再運行下面命令查看擴展後結果：
# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 4.0G 995M 3.1G 25% /
devtmpfs devtmpfs 915M 0 915M 0% /dev
tmpfs tmpfs 921M 0 921M 0% /dev/shm
tmpfs tmpfs 921M 8.4M 913M 1% /run
tmpfs tmpfs 921M 0 921M 0% /sys/fs/cgroup
/dev/mapper/centos-usr xfs 4.9G 1.6G 3.4G 33% /usr
/dev/mapper/centos-home xfs 9.8G 391M 9.4G 4% /home
/dev/mapper/centos-var xfs 2.4G 469M 1.9G 20% /var
/dev/sda1 xfs 97M 66M 31M 69% /boot