Linux下調整根目錄的空間大小

http://blog.csdn.net/andy_yf/article/details/7831482

一、目的

在使用CentOS6.3版本linux系統的時候，發現根目錄(/)的空間不是很充足，而其他目錄空間有很大的空閒，所以本文主要是針對現在已有的空間進行調整。首先，先來查看一下系統的空間分配情況：

 

[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                       50G   14G   34G  30% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot
/dev/mapper/vg_centos-lv_home
                      404G  670M  382G   1% /home

[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                       50G   14G   34G  30% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot
/dev/mapper/vg_centos-lv_home
                      404G  670M  382G   1% /home

下面的詳細步驟部分將從vg_centos-lv_home分區下取出100G的空間添加到/vg_centos-lv_root分區上去。  

 

二、詳細步驟

1、卸載vg_centos-lv_home分區

 

[root@CentOS-78 /]# umount /home

[root@CentOS-78 /]# umount /home

此時在用df命令查看將會發現/home目錄已經看不見了，如下所示：  

 

 

[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                       50G   14G   34G  30% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot

[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                       50G   14G   34G  30% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot

 

2、從新設定vg_home-lv_home的大小

 

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_home 282G
resize2fs 1.41.12 (17-May-2010)
Please run 'e2fsck -f /dev/mapper/vg_centos-lv_home' first.

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_home 282G
resize2fs 1.41.12 (17-May-2010)
Please run 'e2fsck -f /dev/mapper/vg_centos-lv_home' first.

這一步設定vg_home-lv_home大小沒有成功，系統提示我們先運行下面的命令，操作如下：  

 

 

[root@CentOS-78 /]# e2fsck -f /dev/mapper/vg_centos-lv_home
e2fsck 1.41.12 (17-May-2010)
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/mapper/vg_centos-lv_home: 1386/26836992 files (0.9% non-contiguous), 1855856/107344896 blocks

[root@CentOS-78 /]# e2fsck -f /dev/mapper/vg_centos-lv_home
e2fsck 1.41.12 (17-May-2010)
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/mapper/vg_centos-lv_home: 1386/26836992 files (0.9% non-contiguous), 1855856/107344896 blocks

從新設定vg_home-lv_home的大小：  

 

 

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_home 282G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/vg_centos-lv_home to 73924608 (4k) blocks.
Begin pass 2 (max = 43)
Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 3 (max = 3276)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 4 (max = 266)
Updating inode references     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/mapper/vg_centos-lv_home is now 73924608 blocks long.

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_home 282G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/vg_centos-lv_home to 73924608 (4k) blocks.
Begin pass 2 (max = 43)
Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 3 (max = 3276)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 4 (max = 266)
Updating inode references     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/mapper/vg_centos-lv_home is now 73924608 blocks long.

檢查是否成功：  

 

 

[root@CentOS-78 /]# mount /home
[root@CentOS-78 /]#
[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                       50G   14G   34G  30% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot
/dev/mapper/vg_centos-lv_home
                      278G  663M  263G   1% /home
[root@CentOS-78 /]#

[root@CentOS-78 /]# mount /home
[root@CentOS-78 /]#
[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                       50G   14G   34G  30% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot
/dev/mapper/vg_centos-lv_home
                      278G  663M  263G   1% /home
[root@CentOS-78 /]#

3、將lv_home邏輯分區減小到指定大小  

 

 

[root@CentOS-78 /]# lvreduce -L 282G /dev/mapper/vg_centos-lv_home
  WARNING: Reducing active and open logical volume to 282.00 GiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv_home? [y/n]: y
  Reducing logical volume lv_home to 282.00 GiB
  Logical volume lv_home successfully resized
[root@CentOS-78 /]#

[root@CentOS-78 /]# lvreduce -L 282G /dev/mapper/vg_centos-lv_home
  WARNING: Reducing active and open logical volume to 282.00 GiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv_home? [y/n]: y
  Reducing logical volume lv_home to 282.00 GiB
  Logical volume lv_home successfully resized
[root@CentOS-78 /]#

我認爲這個命令是將已經減少的100G空間拿到系統公共的區域，可以被其他分區加載和利用。

 

查詢卷組的信息：

 

[root@CentOS-78 /]# vgdisplay
  --- Volume group ---
  VG Name               vg_centos
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               465.27 GiB
  PE Size               4.00 MiB
  Total PE              119109
  Alloc PE / Size       86472 / 337.78 GiB
  Free  PE / Size       32637 / 127.49 GiB
  VG UUID               1k4ooN-RFV9-uyf1-uMYf-aERG-YaGs-ZNoSD6

[root@CentOS-78 /]# vgdisplay
  --- Volume group ---
  VG Name               vg_centos
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               465.27 GiB
  PE Size               4.00 MiB
  Total PE              119109
  Alloc PE / Size       86472 / 337.78 GiB
  Free  PE / Size       32637 / 127.49 GiB
  VG UUID               1k4ooN-RFV9-uyf1-uMYf-aERG-YaGs-ZNoSD6

 

Free PE / Size指定的應該是現在可在分配的空間。

4、增加vg_centos-lv_root分區的大小  

將可用的空間添加到vg_centos-lv_root分區上面：

 

[root@CentOS-78 /]# lvextend -L +127.40G /dev/mapper/vg_centos-lv_root
  Rounding up size to full physical extent 127.40 GiB
  Extending logical volume lv_root to 177.40 GiB
  Logical volume lv_root successfully resized
[root@CentOS-78 /]#

[root@CentOS-78 /]# lvextend -L +127.40G /dev/mapper/vg_centos-lv_root
  Rounding up size to full physical extent 127.40 GiB
  Extending logical volume lv_root to 177.40 GiB
  Logical volume lv_root successfully resized
[root@CentOS-78 /]#

從新設定該分區的大小：

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg_centos-lv_root is mounted on /; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 12
Performing an on-line resize of /dev/mapper/vg_centos-lv_root to 46504960 (4k) blocks.
The filesystem on /dev/mapper/vg_centos-lv_root is now 46504960 blocks long.

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg_centos-lv_root is mounted on /; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 12
Performing an on-line resize of /dev/mapper/vg_centos-lv_root to 46504960 (4k) blocks.
The filesystem on /dev/mapper/vg_centos-lv_root is now 46504960 blocks long.

5、再次查看分區大小  

 

 

[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                      175G   14G  153G   9% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot
/dev/mapper/vg_centos-lv_home
                      278G  663M  263G   1% /home

[root@CentOS-78 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
                      175G   14G  153G   9% /
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             485M   37M  423M   8% /boot
/dev/mapper/vg_centos-lv_home
                      278G  663M  263G   1% /home

我們發現vg_centos-lv_root分區的空間已經增加了125G，之所以比lv_home減少的空間要多25G主要是由於我們把系統所有的可用的空間都加在了lv_root分區。  

 

三、所遇到的問題

1、在卸載/home目錄的時候失敗

可先執行如下fuser命令，然後再umount即可：

 

[root@CentOS-78 /]# fuser -m /home
[root@CentOS-78 /]#

[root@CentOS-78 /]# fuser -m /home
[root@CentOS-78 /]#

2、設定完lv_home的大小，再次mount該分區時，發現用df命令無法看到給分區，此時只要在mount一次即可  

 

3、在設定lv_root的大小時，不要把Free PE / Size的空間全部都用上，這很可能會出現Free PE空間不足的現象，建議保留一點Free PE的空間。

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參考：

http://hi.baidu.com/%B7%E7%B6%C0/blog/item/c4aa9a81b204dbc89023d956.html

http://qianxunniao.iteye.com/blog/1393726