CentOS 7擴展根分區

VirtualBox中安裝了CentOS 7，給同事用來作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：

列出各分區使用狀況：

# 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

能夠看見 /dev/mapper/centos-root 已經使用了100%，咱們準備爲它擴容。

在VirtualBox中添加一塊新的虛擬磁盤：

先關閉操做系統。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。我增長了一塊3GiB大小的虛擬磁盤，保存後再次啓動虛擬機。

建立新分區

先看一下現有磁盤狀況：

# fdisk -l

結果：

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
...
...
...

已經能夠看到新磁盤/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  --建立新分區
p  --建立主分區
<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紅了一個區。
再看一下現有磁盤狀況：

# fdisk -l

已經多出了一個新分區：

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
  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
  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

能夠看到當前卷分組名爲"centos"。

爲以前新增的分區建立物理卷：

# pvcreate /dev/sdb1

提示是否擦除xfs簽名，我選了y：

WARNING: xfs signature detected on /dev/sdb1 at offset 0. Wipe it? [y/n] y
  Wiping xfs signature on /dev/sdb1.
  Physical volume "/dev/sdb1" successfully created

查看結果：

# pvdisplay

已經看到新建立的3GiB大小的物理卷：

--- 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

提示成功擴展。

下面查看一下邏輯卷：

# lvdisplay

能夠看到/dev/centos/root目前的LV Size是1000MiB。

下面擴展邏輯卷/dev/centos/root:

# lvextend -L +3G /dev/centos/root

注：+3G是咱們新增長的分區大小。

擴展後，還要執行一步：

# xfs_growfs /dev/centos/root

將文件系統擴大。
完成。

由於安裝CentOS用的xfs分區，因此使用命令xfs_growfs擴展文件系統大小。不然的話使用resize2fs命令。

查看結果：

# df -Th

/root已經擴充到4GiB：

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