CentOS7下根分区扩容

linux

为更好熟悉CentOS7，日前在PC上安装了VirtualBox软件来跑CentOS7练练手。虚机CentOS7暂采用1Core CPU，2G Mem，10G Disk配置，最小化安装并升级下系统后快照备份存档以备后用，后期可根据需要随时调整配置。
今天准备整个PostgreSQL玩玩的，首先需要对10G的磁盘进行扩展。安装系统时选择的是默认分区方案，root分区是用lvm管理的，分区格式是xfs。如下所示：

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[root@myprecious ~]# df -Th
Filesystem                         Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos_myprecious-root xfs       8.5G  855M  7.7G  10% /
devtmpfs                           devtmpfs  487M     0  487M   0% /dev
tmpfs                              tmpfs     497M     0  497M   0% /dev/shm
tmpfs                              tmpfs     497M  6.5M  491M   2% /run
tmpfs                              tmpfs     497M     0  497M   0% /sys/fs/cgroup
/dev/sda1                          xfs       497M  124M  374M  25% /boot
tmpfs                              tmpfs     100M     0  100M   0% /run/user/0
[root@myprecious ~]#

所以扩展root分区就很容易了。首先再添加一块虚拟磁盘到虚机，重启后fdisk -l查看虚拟磁盘是否被识别。如下，可以看到新增磁盘被标记为/dev/sdb，有53.7G的空间。

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[root@myprecious ~]# 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 / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0008ee5f
    
   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: 53.7 GB, 53687091200 bytes, 104857600 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_myprecious-root: 8.3 GB, 53724839936 bytes, 104931328 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_myprecious-swap: 1073 MB, 1073741824 bytes, 2097152 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
    
[root@myprecious ~]#

创建磁盘分区

惯例，为/dev/sdb磁盘创建分区，如下：

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[root@myprecious ~]# 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 0x4cb24dcf.
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): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   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
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-624152, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-624152, default 624152): 
Using default value 624152
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): L
 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris        
 1  FAT12           39  Plan 9          82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      3c  PartitionMagic  83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       40  Venix 80286     84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      41  PPC PReP Boot   85  Linux extended  c7  Syrinx         
 5  Extended        42  SFS             86  NTFS volume set da  Non-FS data    
 6  FAT16           4d  QNX4.x          87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS       4e  QNX4.x 2nd part 88  Linux plaintext de  Dell Utility   
 8  AIX             4f  QNX4.x 3rd part 8e  Linux LVM       df  BootIt         
 9  AIX bootable    50  OnTrack DM      93  Amoeba          e1  DOS access     
 a  OS/2 Boot Manag 51  OnTrack DM6 Aux 94  Amoeba BBT      e3  DOS R/O        
 b  W95 FAT32       52  CP/M            9f  BSD/OS          e4  SpeedStor      
 c  W95 FAT32 (LBA) 53  OnTrack DM6 Aux a0  IBM Thinkpad hi eb  BeOS fs        
 e  W95 FAT16 (LBA) 54  OnTrackDM6      a5  FreeBSD         ee  GPT            
 f  W95 Ext'd (LBA) 55  EZ-Drive        a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            56  Golden Bow      a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    5c  Priam Edisk     a8  Darwin UFS      f1  SpeedStor      
12  Compaq diagnost 61  SpeedStor       a9  NetBSD          f4  SpeedStor      
14  Hidden FAT16 <3 63  GNU HURD or Sys ab  Darwin boot     f2  DOS secondary  
16  Hidden FAT16    64  Novell Netware  af  HFS / HFS+      fb  VMware VMFS    
17  Hidden HPFS/NTF 65  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE 
18  AST SmartSleep  70  DiskSecure Mult b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 75  PC/IX           bb  Boot Wizard hid fe  LANstep        
1c  Hidden W95 FAT3 80  Old Minix       be  Solaris boot    ff  BBT            
1e  Hidden W95 FAT1
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: 53.7 GB, 53687091200 bytes
16 heads, 63 sectors/track, 624152 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x4cb24dcf
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      624152   314572576+  8e  Linux LVM
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@myprecious ~]#

整块磁盘/dev/sdb被分区为/dev/sdb1，将该分区格式化为xfs。

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[root@myprecious ~]# mkfs.xfs -f /dev/sdb1

创建物理卷PV

查看并创建物理卷PV：

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[root@myprecious ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos_myprecious
  PV Size               9.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              2434
  Free PE               0
  Allocated PE          2434
  PV UUID               0bE8O8-syyl-TSyE-p9Bv-sZEJ-3GkE-vNC4XB
  
[root@myprecious ~]# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created
[root@myprecious ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               centos_myprecious
  PV Size               9.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              2434
  Free PE               0
  Allocated PE          2434
  PV UUID               0bE8O8-syyl-TSyE-p9Bv-sZEJ-3GkE-vNC4XB
  
  "/dev/sdb1" is a new physical volume of "53.7 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name               
  PV Size               53.7 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               8Z7hoj-Ub4d-xLr3-z7ti-Z5zM-oVTv-TuLtv7
   
[root@myprecious ~]#

创建卷组VG

以上，PV /dev/sdb1已创建完成，但未被分配。将PV /dev/sdb1分配到系统的卷组VG上，这里为centos_myprecious，如下：

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[root@myprecious ~]# vgdisplay
  --- Volume group ---
  VG Name               centos_myprecious
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               59.50 GiB
  PE Size               4.00 MiB
  Total PE              15233
  Alloc PE / Size       13065 / 51.04 GiB
  Free  PE / Size       2168 / 8.47 GiB
  VG UUID               jvcc7L-quO1-MQOz-KDX3-v4QN-ES9G-q4h7H7
   
[root@myprecious ~]# vgextend centos_myprecious /dev/sdb1
  Physical volume "/dev/sdb1" successfully created
  Volume group "centos_myprecious" successfully extended
[root@myprecious ~]#

查看逻辑卷LV

在分配完卷组后，就可以见卷组中未分配的空间分配给root分区了，这里为/dev/sdb1分区。

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[root@myprecious ~]# lvdisplay
  --- Logical volume ---
  LV Path                /dev/centos_myprecious/root
  LV Name                root
  VG Name                centos_myprecious
  LV UUID                KqVmPb-MNpe-VPmH-ato8-aeVU-JbOz-HNgG0M
  LV Write Access        read/write
  LV Creation host, time myprecious, 2017-02-20 14:35:34 +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
  
  --- Logical volume ---
  LV Path                /dev/centos_myprecious/swap
  LV Name                swap
  VG Name                centos_myprecious
  LV UUID                4HGA1K-1bYu-Vvmx-j70O-l0U7-NwvG-etzOF6
  LV Write Access        read/write
  LV Creation host, time myprecious, 2017-02-20 14:35:33 +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

扩展逻辑卷LV时的小插曲

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[root@myprecious ~]# lvextend -l 100%FREE /dev/centos_myprecious/root 
  Size of logical volume centos_myprecious/root changed from 8.47 GiB (2168 extents) to 50.04 GiB (12809 extents).
  Logical volume root successfully resized.
[root@myprecious ~]# e2fsck -f /dev/centos_myprecious/root 
e2fsck 1.42.9 (28-Dec-2013)
/dev/centos_myprecious/root is mounted.
e2fsck: Cannot continue, aborting.
    
[root@myprecious ~]# resize2fs /dev/centos_myprecious/root 
resize2fs 1.42.9 (28-Dec-2013)
resize2fs: Bad magic number in super-block while trying to open /dev/centos_myprecious/root
Couldn't find valid filesystem superblock.
[root@myprecious ~]# df -h
Filesystem                          Size  Used Avail Use% Mounted on
/dev/mapper/centos_myprecious-root  8.5G  854M  7.7G  10% /
devtmpfs                            487M     0  487M   0% /dev
tmpfs                               497M     0  497M   0% /dev/shm
tmpfs                               497M  6.5M  491M   2% /run
tmpfs                               497M     0  497M   0% /sys/fs/cgroup
/dev/sda1                           497M  124M  374M  25% /boot
tmpfs                               100M     0  100M   0% /run/user/0
[root@myprecious ~]#

在使用resize2fs操作后报错，查看分区信息发现根分区并没有变多，甚至重启后执行resize2fs操作依旧报错。之前的centos6扩展ext2/ext3/ext4明明都是好好的，问题出在哪儿呢？查找资料，发现是resize2fs不能扩展xfs分区所致。扩展xfs分区需要使用xfs_growfs。如下：

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[root@myprecious ~]# xfs_growfs /dev/centos_myprecious/root 
meta-data=/dev/mapper/centos_myprecious-root isize=256    agcount=4, agsize=555008 blks
         =                       sectsz=512   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=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 2220032 to 13116416
[root@myprecious ~]# df -h
Filesystem                          Size  Used Avail Use% Mounted on
/dev/mapper/centos_myprecious-root   51G  904M   50G   2% /
devtmpfs                            487M     0  487M   0% /dev
tmpfs                               497M     0  497M   0% /dev/shm
tmpfs                               497M  6.5M  491M   2% /run
tmpfs                               497M     0  497M   0% /sys/fs/cgroup
/dev/sda1                           497M  124M  374M  25% /boot
tmpfs                               100M     0  100M   0% /run/user/0
[root@myprecious ~]#

使用xfs_growfs后，根分区被正常扩展。没注意到centos7中根分区已经有centos6中的ext4变更为xfs，相应的扩展分区的命令变更为xfs_growfs。
有时候真的是不能想当然，一个小细节的差异也会导致达不到预期的效果。

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本文标题:CentOS7下根分区扩容

文章作者:Jeff

发布时间:2017-02-21, 10:46:15

最后更新:2017-05-04, 15:02:54

原始链接:https://opstrip.com/2017/02/21/root-partition-expansion-for-centos7/

许可协议: "署名-非商用-相同方式共享 4.0" 转载请保留原文链接及作者。

文章目录
  1. 1. 创建磁盘分区
  2. 2. 创建物理卷PV
  3. 3. 创建卷组VG
  4. 4. 查看逻辑卷LV
  5. 5. 扩展逻辑卷LV时的小插曲