Linux磁盘扩容
Linux磁盘扩容的磁盘扩容分为两个场景，一个是新增一个磁盘，另一个是在原有磁盘扩容。
新增一个磁盘
1、添加磁盘
物理机添加硬盘，虚拟机新增硬盘
有条件的情况下提前备份数据
2、检查新磁盘是否被系统识别
bash
# 查看所有块设备
lsblk
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 40G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 39G 0 part
├─centos-root 253:0 0 35.1G 0 lvm /
└─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk <-- 新磁盘
sdc 8:32 0 20G 0 disk <-- 新磁盘
sr0 11:0 1 4.4G 0 rom /run/media/xuxh/CentOS 7 x86_643、对sdb进行分区，20G为一个盘
bash
# 进入 fdisk 交互界面
sudo fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
欢迎使用 fdisk（util-linux 2.23.2）。
Changes will remain in memory only, until you decide to write them.
更改将仅保留在内存中，直到您决定将其写入。
Be careful before using the write command.
使用写入命令前请务必小心。
Command (m for help): n (新建分区)
命令（按m键获取帮助）：
Partition type:
分区类型：
p primary (0 primary, 0 extended, 4 free)
p 主分区（0 个主分区，0 个扩展分区，4 个空闲分区）
e extended
e代表"extended"，即"扩展的"
Select (default p): p
选择（默认p）：
Partition number (1-4, default 1):1
分区号（1-4，默认为1）：
First sector (2048-41943039, default 2048): 回车
第一扇区（2048-41943039，默认值2048）：
Using default value 2048
使用默认值2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): 回车
最后一个扇区，+扇区数或+大小{K,M,G}（2048-41943039，默认值41943039）：
Using default value 41943039
使用默认值41943039
Partition 1 of type Linux and of size 20 GiB is set
已设置类型为Linux、大小为20 GiB的分区1
Command (m for help):w(写入分区表并退出)
The partition table has been altered!
分区表已被更改！
Calling ioctl() to re-read partition table.
Syncing disks.
调用ioctl()函数以重新读取分区表。
正在同步磁盘。4、对sdc进行分区，20G为5G+5G+10G（不分配）
bash
fdisk /dev/sdc
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.
# 分区1
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): 1
First sector (2048-41943039, default 2048): 回车
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +5G
Partition 1 of type Linux and of size 5 GiB is set
# 分区2
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p
Partition number (2-4, default 2): 2
First sector (10487808-41943039, default 10487808): 回车
Using default value 10487808
Last sector, +sectors or +size{K,M,G} (10487808-41943039, default 41943039): +5G
Partition 2 of type Linux and of size 5 GiB is set
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): p
Partition number (3,4, default 3):回车
First sector (20973568-41943039, default 20973568):回车
Using default value 20973568
Last sector, +sectors or +size{K,M,G} (20973568-41943039, default 41943039):回车
Using default value 41943039
Partition 3 of type Linux and of size 10 GiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.5、验证
bash
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 40G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 39G 0 part
├─centos-root 253:0 0 35.1G 0 lvm /
└─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 20G 0 part
sdc 8:32 0 20G 0 disk
├─sdc1 8:33 0 5G 0 part
├─sdc2 8:34 0 5G 0 part
└─sdc3 8:35 0 10G 0 part
sr0 11:0 1 4.4G 0 rom /run/media/xuxh/CentOS 7 x86_645.1、删除错误分区
bash
lsblk
sdc 8:32 0 20G 0 disk
├─sdc1 8:33 0 15G 0 part
└─sdc3 8:35 0 5G 0 part
fdisk /dev/sdc
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): d
Partition number (1,3, default 3): 1
Partition 1 is deleted
Command (m for help): d
Selected partition 3
Partition 3 is deleted
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.删除后再重新验证一下，没问题就重新开始
6、格式化
mkfs文件系统类型也有讲究，最好是百度一下再决定下一步
bash
sudo mkfs.ext4 /dev/sdb1
sudo mkfs.ext4 /dev/sdc1
sudo mkfs.ext4 /dev/sdc27、挂载分区
bash
sudo mkdir -p /mnt/disk_sdb1 # 对应 sdb1
sudo mkdir -p /mnt/disk_sdc1 # 对应 sdc1
sudo mkdir -p /mnt/disk_sdc2 # 对应 sdc27.1、临时挂载
手动挂载，重启失效
bash
sudo mount /dev/sdb1 /mnt/disk_sdb1
sudo mount /dev/sdc1 /mnt/disk_sdc1
sudo mount /dev/sdc2 /mnt/disk_sdc2
# 验证
df -hT | grep -E "sdb1|sdc1|sdc2"
/dev/sdb1 xfs 20G 33M 20G 1% /mnt/disk_sdb1
/dev/sdc1 xfs 5.0G 33M 5.0G 1% /mnt/disk_sdc1
/dev/sdc2 xfs 5.0G 33M 5.0G 1% /mnt/disk_sdc27.2、永久挂载
开机自动挂载
bash
sudo blkid /dev/sdb1 /dev/sdc1 /dev/sdc2
/dev/sdb1: UUID="81d0492e-d180-4f83-a3d6-c932eba06a35" TYPE="ext4"
/dev/sdc1: UUID="83202952-2836-4d40-81bd-0c8f26660f3d" TYPE="ext4"
/dev/sdc2: UUID="fde4c7ee-7f5c-4a8e-a131-16761df483d3" TYPE="ext4"操作前可以备份fstab，看个人
bash
sudo cp /etc/fstab /etc/fstab.bak
sudo vi /etc/fstab
UUID=81d0492e-d180-4f83-a3d6-c932eba06a35 /mnt/data_sdb1 ext4 defaults 0 0
UUID=83202952-2836-4d40-81bd-0c8f26660f3d /mnt/data_sdc1 ext4 defaults 0 0
UUID=fde4c7ee-7f5c-4a8e-a131-16761df483d3 /mnt/data_sdc2 ext4 defaults 0 08、验证
bash
sudo mount -a # 不报错
df -h | grep -E "data_sdb1|data_sdc1|data_sdc2"
/dev/sdb1 20G 45M 19G 1% /mnt/data_sdb1
/dev/sdc1 4.8G 20M 4.6G 1% /mnt/data_sdc1
/dev/sdc2 4.8G 20M 4.6G 1% /mnt/data_sdc2原有磁盘扩容（fdisk）
把sdc3的10加到sdc2的5G，变成15G。
前提是 sdc2 和 sdc3 在磁盘上是连续的（即 sdc3 紧跟在 sdc2 后面）。根据之前的分区创建顺序（sdc1、sdc2、sdc3），它们是连续的，可以合并。
还有一种用parted操作，但是我还没试过，后面试过再补充了
1、卸载分区
bash
sudo umount /dev/sdc2 /dev/sdc32、删除分区
bash
[root@localhost /]# sudo fdisk /dev/sdc
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.
# 记一下分区
Command (m for help): p
Disk /dev/sdc: 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: 0xdb9b3529
Device Boot Start End Blocks Id System
/dev/sdc1 2048 10487807 5242880 83 Linux
/dev/sdc2 10487808 20973567 5242880 83 Linux
/dev/sdc3 20973568 41943039 10484736 83 Linux
# 删除分区3
Command (m for help): d
Partition number (1-3, default 3): 3
Partition 3 is deleted
# 删除分区2
Command (m for help): d
Partition number (1,2, default 2): 2
Partition 2 is deleted
# 重新创建，注意起始位置
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p
Partition number (2-4, default 2): 2
First sector (10487808-41943039, default 10487808):
Using default value 10487808
Last sector, +sectors or +size{K,M,G} (10487808-41943039, default 41943039):
Using default value 41943039
Partition 2 of type Linux and of size 15 GiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
# 告警
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.说明内核仍在占用 /dev/sdc 上的某个分区（很可能是 /dev/sdc2 还在挂载中，或者有进程在使用它）。因此新分区表无法立即生效。只能重启
bash
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 40G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 39G 0 part
├─centos-root 253:0 0 35.1G 0 lvm /
└─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 20G 0 part /mnt/data_sdb1
sdc 8:32 0 20G 0 disk
├─sdc1 8:33 0 5G 0 part /mnt/data_sdc1
└─sdc2 8:34 0 15G 0 part /mnt/data_sdc2
sr0 11:0 1 4.4G 0 rom重启后分区正常
3、验证文件系统
bash
df -h /mnt/data_sdc2
Filesystem Size Used Avail Use% Mounted on
/dev/sdc2 4.8G 20M 4.6G 1% /mnt/data_sdc24、卸载/dev/sdc2
bash
sudo umount /mnt/data_sdc25、扩展文件系统
bash
# 1. 检查文件系统（此时未挂载，可以安全执行）
sudo e2fsck -f /dev/sdc2
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/sdc2: 18/327680 files (0.0% non-contiguous), 58462/1310720 blocks
# 2. 扩展文件系统到分区大小
sudo resize2fs /dev/sdc2
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/sdc2 to 3931904 (4k) blocks.
The filesystem on /dev/sdc2 is now 3931904 blocks long.
# 3. 重新挂载
sudo mount /dev/sdc2 /mnt/data_sdc2
# 4. 验证
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 40G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 39G 0 part
├─centos-root 253:0 0 35.1G 0 lvm /
└─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
sdb 8:16 0 20G 0 disk
└─sdb1 8:17 0 20G 0 part /mnt/data_sdb1
sdc 8:32 0 20G 0 disk
├─sdc1 8:33 0 5G 0 part /mnt/data_sdc1
└─sdc2 8:34 0 15G 0 part /mnt/data_sdc2
sr0 11:0 1 4.4G 0 rom报错
1、挂在磁盘后，开机就进入维护页面
系统进入了紧急模式（emergency mode），核心原因是 /etc/fstab 文件中的挂载选项存在语法错误。具体错误为：EXT4-fs (sdb1): Unrecognized mount option "default" or missing value
应该是defaults
- 输入root密码
- 检查并修复/etc/fstab
- mount -o remount,rw /
- vi /etc/fstab
- 找到sdb1，删除default或者重新检查语句
- 重新挂载mount -a，没有报错就可以
- 重启 reboot