LVMの設定

　CentOSを新規にインストールしたら、/homeにかなり容量が割り当てられていました。インストール後にこれらを/rootに割り当てなおす方法を以下にまとめました。

　LVMは使えるようになると、パーティション管理が非常に楽になりとても便利です。

現状の確認

/homeに230G以上割り当てられています。

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       50G  2.1G   45G   5% /
tmpfs                 7.2G     0  7.2G   0% /dev/shm
/dev/vda1             485M   37M  423M   8% /boot
/dev/mapper/VolGroup-lv_home
                      232G  188M  220G   1% /home

# lvdisplay
(実行結果を抜粋)
  --- Logical volume ---
  LV Path                /dev/VolGroup/lv_home
  LV Name                lv_home
  VG Name                VolGroup
  LV UUID                6YaBB6-sXdC-IC76-Wjgo-vgou-bGvK-W4SWMg
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2014-05-19 22:19:15 -0400
  LV Status              available
  # open                 1
  LV Size                235.29 GiB
  Current LE             60234
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

/homeの割り当ての削減

　5GBにまで割り当てを削減します。

# umount /dev/mapper/VolGroup-lv_home
# e2fsck -f /dev/mapper/VolGroup-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/VolGroup-lv_home: 11/15425536 files (0.0% non-contiguous), 1016011/61679616 blocks
# resize2fs /dev/mapper/VolGroup-lv_home 5G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/VolGroup-lv_home to 1310720 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_home is now 1310720 blocks long.
# mount /dev/mapper/VolGroup-lv_home
# lvresize -L -230G /dev/mapper/VolGroup-lv_home
  WARNING: Reducing active and open logical volume to 5.29 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 5.29 GiB
  Logical volume lv_home successfully resized

空き容量の確認

　230GB空き容量があるのがわかります。

# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  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               292.48 GiB
  PE Size               4.00 MiB
  Total PE              74874
  Alloc PE / Size       15994 / 62.48 GiB
  Free  PE / Size       58880 / 230.00 GiB
  VG UUID               0djUbi-heIw-JBd0-LFKv-uKlK-P7CW-P5Z0e2

/rootへの割り当て

　空き容量を全て/rootに割り当てます。

# lvresize -L +230G /dev/mapper/VolGroup-lv_root
  Extending logical volume lv_root to 280.00 GiB
  Logical volume lv_root successfully resized
# resize2fs /dev/mapper/VolGroup-lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup-lv_root is mounted on /; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 18
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 73400320 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_root is now 73400320 blocks long.

割り当ての再確認

　/rootに割り当てが正しくなされていることを確認しました。

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                      276G  2.1G  260G   1% /
tmpfs                 7.2G     0  7.2G   0% /dev/shm
/dev/vda1             485M   37M  423M   8% /boot
/dev/mapper/VolGroup-lv_home
                      5.0G  160M  4.6G   4% /home