Linux(Redhat6.9) 磁盘格式化/扩容

预备知识

逻辑卷管理LVM是一个硬盘系统工具。无论在Linux或者其他类似的系统，都是非常的好用。传统分区使用固定大小分区，重新调整大小十分麻烦。但是，LVM可以创建和管理“逻辑”卷，而不是直接使用物理硬盘。可以让管理员弹性的管理逻辑卷的扩大缩小，操作简单，而不损坏已存储的数据。可以随意将新的硬盘添加到LVM，以直接扩展已经存在的逻辑卷。LVM并不需要重启就可以让内核知道分区的存在。

lvm

图中顶部，首先是实际的物理磁盘及其划分的分区和其上的物理卷（PV）。一个或多个物理卷可以用来创建卷组（VG）。然后基于卷组可以创建逻辑卷（LV）。只要在卷组中有可用空间，就可以随心所欲的创建逻辑卷。文件系统就是在逻辑卷上创建的，然后可以在操作系统挂载和访问。

pv/vg/lv

磁盘的扩容主要依据就是lvm

磁盘信息

lsblk与df -hT

[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 17.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk 
[root@micocube ~]# df -hT
Filesystem           Type   Size  Used Avail Use% Mounted on
/dev/mapper/vg_micocube-lv_root
                     ext4    18G  1.9G   15G  12% /
tmpfs                tmpfs  939M     0  939M   0% /dev/shm
/dev/sda1            ext4   477M   41M  412M   9% /boot

可以看到sdb的类型是disk，没有分区，也没有挂载点，就是个空白盘

将空白磁盘直接格式化，挂载到/data

如何将其挂上去用呢？最简单的方法，就是将整个磁盘格式化，不分区，直接使用，但是用这种方法之后磁盘不再支持扩容

[root@micocube ~]# mkfs -t ext4 /dev/sdb 
mke2fs 1.41.12 (17-May-2010)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
655360 inodes, 2621440 blocks
131072 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2684354560
80 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

Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 29 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

临时挂载

[root@micocube ~]# mkdir /data
[root@micocube ~]# mount /dev/sdb /data/
[root@micocube ~]# df -hT
Filesystem           Type   Size  Used Avail Use% Mounted on
/dev/mapper/vg_micocube-lv_root
                     ext4    18G  1.9G   15G  12% /
tmpfs                tmpfs  939M     0  939M   0% /dev/shm
/dev/sda1            ext4   477M   41M  412M   9% /boot
/dev/sdb             ext4   9.8G   23M  9.2G   1% /data

永久挂载

[root@micocube ~]# vi /etc/fstab 


#
# /etc/fstab
# Created by anaconda on Sun Apr 28 05:50:32 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/vg_micocube-lv_root /                       ext4    defaults        1 1
UUID=57ad23fa-8c2f-42f8-91c1-01e5bcf4a058 /boot                   ext4    defaults        1 2
/dev/mapper/vg_micocube-lv_swap swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/sdb                /data                   ext4    defaults        0 0

# reboot 
[root@micocube ~]# reboot

[root@micocube ~]# df -hT
Filesystem           Type   Size  Used Avail Use% Mounted on
/dev/mapper/vg_micocube-lv_root
                     ext4    18G  1.9G   15G  12% /
tmpfs                tmpfs  939M     0  939M   0% /dev/shm
/dev/sda1            ext4   477M   41M  412M   9% /boot
/dev/sdb             ext4   9.8G   23M  9.2G   1% /data

## 可以看到sdb已经挂载上去了
[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 17.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk

如果想给/(根)挂载点扩容，咋办？

[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 17.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk /data

可以看到/根挂载点的类型是lvm，这说明他可以动态扩容，为了试验，我加了一块15G的硬盘:

[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 17.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk /data
sdc                              8:32   0   15G  0 disk

接下来我会把sdc扩容到dev/vg_micocube/lv_root 即/节点
给sdc分区，为了方便，这里只分一个区,注意代码8e，即Changed system type of partition 1 to 8e (Linux LVM)，分区的系统类型修改为lvm，

[root@micocube ~]# fdisk /dev/sdc
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x66a87408.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1958, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1958, default 1958): 
Using default value 1958

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/sdc: 16.1 GB, 16106127360 bytes
255 heads, 63 sectors/track, 1958 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x66a87408

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1        1958    15727603+  8e  Linux LVM

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

接着创建pv，扩展vg，扩展lv，resize2fs

[root@micocube ~]# pvcreate /dev/sdc1 
  Physical volume "/dev/sdc1" successfully created
## 查看所有vg
[root@micocube ~]# vgs
  VG          #PV #LV #SN Attr   VSize  VFree
  vg_micocube   1   2   0 wz--n- 19.51g    0 
## 扫描vg
[root@micocube ~]# vgscan 
  Reading all physical volumes.  This may take a while...
  Found volume group "vg_micocube" using metadata type lvm2
[root@micocube ~]# vgextend vg_micocube /dev/sdc1 
[root@micocube ~]# lvextend -L +15G /dev/mapper/vg_micocube-lv_root 
  Insufficient free space: 3840 extents needed, but only 3839 available
[root@micocube ~]# lvextend -L +14G /dev/mapper/vg_micocube-lv_root 
  Size of logical volume vg_micocube/lv_root changed from 17.51 GiB (4482 extents) to 31.51 GiB (8066 extents).
  Logical volume lv_root successfully resized.
  [root@micocube ~]# df -hlT
Filesystem           Type   Size  Used Avail Use% Mounted on
/dev/mapper/vg_micocube-lv_root
                     ext4    18G  1.9G   15G  12% /
tmpfs                tmpfs  939M     0  939M   0% /dev/shm
/dev/sda1            ext4   477M   41M  412M   9% /boot
/dev/sdb             ext4   9.8G   23M  9.2G   1% /data
[root@micocube ~]# resize2fs -f /dev/mapper/vg_micocube-lv_root 
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg_micocube-lv_root is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 2
Performing an on-line resize of /dev/mapper/vg_micocube-lv_root to 8259584 (4k) blocks.
The filesystem on /dev/mapper/vg_micocube-lv_root is now 8259584 blocks long.
[root@micocube ~]# df -hlT
Filesystem           Type   Size  Used Avail Use% Mounted on
/dev/mapper/vg_micocube-lv_root
                     ext4    31G  1.9G   28G   7% /
tmpfs                tmpfs  939M     0  939M   0% /dev/shm
/dev/sda1            ext4   477M   41M  412M   9% /boot
/dev/sdb             ext4   9.8G   23M  9.2G   1% /data

### 可以看到已经扩容成功了
[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk /data
sdc                              8:32   0   15G  0 disk 
└─sdc1                           8:33   0   15G  0 part 
  └─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /

如果想给/data节点扩容呢？

emmm，我又重新添加了一块磁盘sdd:

[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk /data
sdc                              8:32   0   15G  0 disk 
└─sdc1                           8:33   0   15G  0 part 
  └─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
sdd                              8:48   0   20G  0 disk

先卸载sdb,umount /dev/sdb或者umount /data

## 将之前写入分区表的 /dev/sdb                /data                   ext4    defaults        0 0 这一行删除
[root@micocube ~]# vi /etc/fstab 
[root@micocube ~]# umount /dev/sdb
umount: /data: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
[root@micocube ~]# fuser -m -v /dev/sdb
                     USER        PID ACCESS COMMAND
/data/:              root       1895 F.... bash
### 这一步可能连接会断，毕竟你用到了/data 重连就好了

因为没有分区，不是lvm类型，肯定是扩容不了的，只能给磁盘重新分区

[root@micocube ~]# fdisk /dev/sdb 
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xe7603f99.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').
### 我想直接改变类型，行不通，只能重新创建分区
Command (m for help): t
No partition is defined yet!

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1305, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1305, default 1305): 
Using default value 1305

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe7603f99

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        1305    10482381   8e  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.

在进行下一步之前，我还想再强调一下pv/vg/lv的关系
一个硬盘分区组成一个pv（物理卷）
一个或者多个pv组成一个vg（卷组）
一个vg可以划分出多个lv（逻辑卷）
创建pv

## 用分区/dev/sdb1创建一个pv
[root@micocube ~]# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created
## 这一阶段并没有什么变化
[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk 
└─sdb1                           8:17   0   10G  0 part 
sdc                              8:32   0   15G  0 disk 
└─sdc1                           8:33   0   15G  0 part 
  └─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
sdd                              8:48   0   20G  0 disk

如果sdb1找不到可以试着重读分区表

## 重读分区表
[root@micocube ~]# partprobe 
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (Device or resource busy).  As a result, it may not reflect all of your changes until after reboot.
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sdc (Device or resource busy).  As a result, it may not reflect all of your changes until after reboot.
Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only.

创建vg

## 用pv(/dev/sdb1)创建一个vg
[root@micocube ~]# vgcreate vg_data /dev/sdb1 
  Volume group "vg_data" successfully created

查看所有vg

## 查看创建的vg
[root@micocube ~]# vgdisplay 
  --- Volume group ---
  VG Name               vg_data
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               9.99 GiB
  PE Size               4.00 MiB
  Total PE              2558
  Alloc PE / Size       0 / 0   
  Free  PE / Size       2558 / 9.99 GiB
  VG UUID               iyB24d-X5KM-mhKR-Lxw1-kL9i-VALO-ez4EnG
   
  --- Volume group ---
  VG Name               vg_micocube
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizableF
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               34.50 GiB
  PE Size               4.00 MiB
  Total PE              8833
  Alloc PE / Size       8578 / 33.51 GiB
  Free  PE / Size       255 / 1020.00 MiB
  VG UUID               KBuu3K-sZ9j-NdYo-RaK3-ajJs-UAQm-3NJK53

创建lv

## -L 后面是分给lv的大小，-n 新建名字为vg_data的lv，所属卷组(vg)为vg_data
[root@micocube ~]# lvcreate -L 9.99G -n vg_data vg_data
  Rounding up size to full physical extent 9.99 GiB
  Logical volume "vg_data" created.

格式化lv

## dev后边第一个是vg 第二个是lv
[root@micocube ~]# mkfs.ext4 /dev/vg_data/vg_data 
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
655360 inodes, 2619392 blocks
130969 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2684354560
80 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

Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 36 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

永久挂载

[root@micocube ~]# vi /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sun Apr 28 05:50:32 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/vg_micocube-lv_root /                       ext4    defaults        1 1
UUID=57ad23fa-8c2f-42f8-91c1-01e5bcf4a058 /boot                   ext4    defaults        1 2
/dev/mapper/vg_micocube-lv_swap swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/vg_data/vg_data                    /data                   ext4    defaults        0 0

重新挂载

### 重新挂载,使/etc/fstab生效
[root@micocube ~]# mount -a

为了测试扩容后数据是否丢失

#### 按惯例先写一些文件，看扩容后是否还存在
[root@micocube ~]# echo 111111111111 >/data/a.txt
[root@micocube ~]# echo 222222222222 >/data/b.txt
[root@micocube ~]# echo 333333333333 >/data/c.txt
[root@micocube ~]# ls /data/
a.txt  b.txt  c.txt  lost+found
[root@micocube ~]# cat /data/*.txt
111111111111
222222222222
333333333333

给sdd分区

### sdd分区
[root@micocube ~]# fdisk /dev/sdd 
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x7a10ae95.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): 
Using default value 2610

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/sdd: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x7a10ae95

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1               1        2610    20964793+  8e  Linux LVM

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

创建pv

### 创建pv
[root@micocube ~]# pvcreate /dev/sdd1 
  Physical volume "/dev/sdd1" successfully created
[root@micocube ~]# vgs
  VG          #PV #LV #SN Attr   VSize  VFree   
  vg_data       1   1   0 wz--n-  9.99g       0 
  vg_micocube   2   2   0 wz--n- 34.50g 1020.00m
  
[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk 
└─sdb1                           8:17   0   10G  0 part 
  └─vg_data-vg_data (dm-2)     253:2    0   10G  0 lvm  /data
sdc                              8:32   0   15G  0 disk 
└─sdc1                           8:33   0   15G  0 part 
  └─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
sdd                              8:48   0   20G  0 disk 
└─sdd1                           8:49   0   20G  0 part

将创建的pv扩展到vg_data卷组中

## 将创建的pv扩展到vg_data卷组中
[root@micocube ~]# vgextend vg_data /dev/sdd1 
  Volume group "vg_data" successfully extended

扩展lv

## 扩展lv
[root@micocube ~]# lvextend -L +20G /dev/vg_data/vg_data 
  Insufficient free space: 5120 extents needed, but only 5118 available
[root@micocube ~]# lvextend -L +19.9G /dev/vg_data/vg_data
  Rounding size to boundary between physical extents: 19.90 GiB.
  Size of logical volume vg_data/vg_data changed from 9.99 GiB (2558 extents) to 29.89 GiB (7653 extents).
  Logical volume vg_data successfully resized.

resize2fs 使扩展生效

## 写入扩展
[root@micocube ~]# resize2fs -f /dev/vg_data/vg_data 
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_data/vg_data is mounted on /data; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/vg_data/vg_data to 7836672 (4k) blocks.

The filesystem on /dev/vg_data/vg_data is now 7836672 blocks long.
### 可以看到sdb和sdd已经合并了
[root@micocube ~]# lsblk
NAME                           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                             11:0    1 55.3M  0 rom  
sda                              8:0    0   20G  0 disk 
├─sda1                           8:1    0  500M  0 part /boot
└─sda2                           8:2    0 19.5G  0 part 
  ├─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
  └─vg_micocube-lv_swap (dm-1) 253:1    0    2G  0 lvm  [SWAP]
sdb                              8:16   0   10G  0 disk 
└─sdb1                           8:17   0   10G  0 part 
  └─vg_data-vg_data (dm-2)     253:2    0 29.9G  0 lvm  /data
sdc                              8:32   0   15G  0 disk 
└─sdc1                           8:33   0   15G  0 part 
  └─vg_micocube-lv_root (dm-0) 253:0    0 31.5G  0 lvm  /
sdd                              8:48   0   20G  0 disk 
└─sdd1                           8:49   0   20G  0 part 
  └─vg_data-vg_data (dm-2)     253:2    0 29.9G  0 lvm  /data

检查文件是否丢失

### 检查文件是否丢失
[root@micocube ~]# ls /data/
a.txt  b.txt  c.txt  lost+found
[root@micocube ~]# cat /data/*.txt
111111111111
222222222222
333333333333
### 未丢失

一次给oracle数据库盘扩容的经历

接手的时候，oracle数据库文件在一个磁盘(/dev/vdb)的vdb7分区里，即类型为part，挂载点为/database/db1，也就是说，没有建lvm(逻辑卷管理)，直接格式化分区,数据库文件全在里边(dbf),150G，已经用了差不多99%，另外加了一块600G的空白磁盘(/dev/vdc)很明显，是不能直接扩容的，因为是开发环境，那就有的搞了，随便停机多久都没问题啊
思路
- 将vdc分区(/dev/sdc1)，分区系统类型为lvm，创建pv/vg(vg_data)/lv(vg_data_lv),挂载到/db/temp(之前不存在)文件夹
- 将/database/db1/下的所有文件拷贝到/db/temp,cp -R /database/db1/* /db/temp/
- vd7 已经是part类型了，那就直接创建pv,之后vgextend vg_data /dev/vdb7,扩展/dev/vdb7到vg_data卷组，lvextend -L +150G /dev/vg_data/vg_data_lv，将原本的150G分配给/dev/vg_data/vg_data_lv
- resize2fs -f /dev/vg_data/vg_data_lv
- 扩容成功之后将/dev/vg_data/vg_data_lv永久挂载到/database/db1
意外：
- resize2fs 报错kernel does not support online resizing：先将/dev/vg_data/vg_data_lv卸载(umount /dev/vg_data/vg_data_lv),再执行resize2fs -f /dev/vg_data/vg_data_lv，之后挂载(mount -a),参考连接：‘filesystem not support online resizing’ 错误
- 扩容之后数据库起不来了，报错：ORA-00205: error in identifying control file, check alert log for more info,造成这个问题的原因是oracle用户访问不了/database/db1，因为扩容的时候用的是root用户创建的，所以没权限，更改用户所属组就好了，chown -R oracle:dba /database/db1 就好了.参考连接：ORACLE11g 实例启动报错 ORA-00205: error in identifying control file, check alert log for more info

总结

使用空白磁盘的时候不要直接格式化整个磁盘，最少给磁盘分个区，分区系统类型设置为lvm(8e),再创建pv/vg/lv，要不然以后扩容麻烦
lvextend命令最好再加上-r 参数
lvextend -r -l +100%FREE /dev/mapper/VolGroup-lv_home
如果不加 -r 参数，需要手动使用 resize2fs /dev/mapper/VolGroup-lv_home才能生效。

lvm 的常用操作

lv/pv/vg	查看显示	创建	删除	扩容	激活	扫描查找
LV	lvdisplay	lvcreate	lvremove	lvextend	lvchange	lvscan
PV	pvdisplay	pvcreate	pvremove		pvchange	pvscan
VG	vgdisplay	vgcreate	vgremove	vgextend	vgchange	vgscan

参考链接

RedHat/CentOS根目录扩容
 linux分区满了，如何进行扩容
 【linux】新添加一块硬盘制作LVM卷并进行分区挂载
 故障处理：磁盘扩容出错：e2fsck: Bad magic number in super-block while trying to open /dev/vdb1

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