centos7扩展根分区
购买的云主机，安装centos7后，发现系统根分区只有8.5G，而云主机硬盘大小是110G。
现在想把剩余的硬盘大小找出来，然后扩容至根分区。
本文主题是：centos扩展根分区。由于阿里云，腾讯云在购买主机时，硬盘大小即为根分区
大小，没有遇到到需要扩容的情况。
1、查看硬盘大小信息
[root@localhost ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 8.5G 1.5G 7.0G 18% / devtmpfs 231M 0 231M 0% /dev tmpfs 241M 0 241M 0% /dev/shm tmpfs 241M 4.3M 237M 2% /run tmpfs 241M 0 241M 0% /sys/fs/cgroup /dev/sda1 494M 124M 371M 25% /boot tmpfs 49M 0 49M 0% /run/user/0 # 发现只有8.5G，总大小没有110G
发现根目录只有8.5G，总大小没有110G，然后使用fdisk -l命令查看，发现剩余的空间在sdb第二个磁盘上：
[root@localhost ~]# fdisk -l Disk /dev/sda: 10.7 GB, 10737418240 bytes, 20971520 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk label type: dos Disk identifier: 0x000f1903 Device Boot Start End Blocks Id System /dev/sda1 * 2048 1026047 512000 83 Linux /dev/sda2 1026048 20971519 9972736 8e Linux LVM Disk /dev/sdb: 107.4 GB, 107374182400 bytes, 209715200 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk /dev/mapper/centos-root: 116.5 GB, 116505182208 bytes, 227549184 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 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 / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes
发现sdb磁盘有3个分区，分别是：sdb1、sdb2、sdb3，上面截图是我完成后的，所以看到sdb只有一个分区。
2、删除分区、磁盘分区
# fdisk /dev/sdb #将磁盘分区 #先删除分区，再将磁盘分为一个区
m -----> 打印help信息
d -----> 删除分区
p -----> 打印sdb磁盘的分区信息
n -----> 创建新分区，进到分区项后，按p直接分区，默认分为一个区，自行选择分区数量。
w -----> 保存分区信息，不然分区无法正确完成。
[root@localhost ~]# 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.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xef6f1f81.
The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.
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 (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-209715199, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-209715199, default 209715199):
Using default value 209715199
Partition 1 of type Linux and of size 100 GiB is set
Command (m for help): p
Disk /dev/sdb: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Disk identifier: 0xef23a9cb
Device Boot Start End Blocks Id System
/dev/sdb1 2048 209715199 104856576 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.3、格式化磁盘
# mkfs.ext4 /dev/sdb #格式化为ext4格式
[root@localhost ~]# mkfs.ext4 /dev/sdb
mke2fs 1.42.9 (28-Dec-2013)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
6553600 inodes, 26214400 blocks
1310720 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2174746624
800 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
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done 4、创建物理卷
# pvcreate /dev/sdb
[root@localhost ~]# pvcreate /dev/sdb WARNING: ext4 signature detected on /dev/sdb at offset 1080. Wipe it? [y/n]: y Wiping ext4 signature on /dev/sdb. Physical volume "/dev/sdb" successfully created
5、查看卷组名称
# vgdisplay -v
# 查看到我的VG Name为“centos”
[root@localhost ~]# vgdisplay -v
Using volume group(s) on command line.
--- 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 9.51 GiB
PE Size 4.00 MiB
Total PE 2434
Alloc PE / Size 2424 / 9.47 GiB
Free PE / Size 10 / 40.00 MiB
VG UUID OyB5dN-0LOk-6vb1-Qmtu-1EQp-1GtB-Szuco0
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID 9SLqUm-dXfi-bNle-wdX1-cnZQ-HCun-nGWdXk
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-06-28 02:34:19 +0800
LV Status available
# open 2
LV Size 1.00 GiB
Current LE 256
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID J3ANyS-BTG5-YJ8M-2Zsq-sBUo-YVWg-jyFmvA
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-06-28 02:34:19 +0800
LV Status available
# open 1
LV Size 8.47 GiB
Current LE 2168
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Physical volumes ---
PV Name /dev/sda2
PV UUID P6xf6f-NPgl-s3Dm-123h-B5e3-NJBh-GbNM1n
PV Status allocatable
Total PE / Free PE 2434 / 106、将物理卷扩展到卷组
# vgextend centos /dev/sdb
[root@localhost ~]# vgextend centos /dev/sdb Volume group "centos" successfully extended
7、将卷组中的空闲空间扩展到根分区逻辑卷
#lvextend -l +100%FREE /dev/centos/root
[root@localhost ~]# lvextend -l +100%FREE /dev/mapper/centos-root Size of logical volume centos/root changed from 8.47 GiB (2168 extents) to 108.50 GiB (27777 extents). Logical volume root successfully resized.
8、刷新根分区
# xfs_growfs /dev/centos/root
[root@localhost ~]# xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=256 agcount=4, agsize=555008 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=2220032, 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=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 2220032 to 284436489、查看扩展是否成功
[root@localhost ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 109G 1.5G 108G 2% / devtmpfs 231M 0 231M 0% /dev tmpfs 241M 0 241M 0% /dev/shm tmpfs 241M 4.3M 237M 2% /run tmpfs 241M 0 241M 0% /sys/fs/cgroup /dev/sda1 494M 124M 371M 25% /boot tmpfs 49M 0 49M 0% /run/user/0
看到根分区已为109G大小，扩展根分区成功！
