How to reduce LVM partition size in RHEL and CentOS

[root@amastest RPM2]# df -Th

??                           % 瞜

/dev/mapper/centos-root xfs       1.6T   10G  1.6T    1% /

devtmpfs                devtmpfs  7.7G     0  7.7G    0% /dev

tmpfs                   tmpfs     7.7G     0  7.7G    0% /dev/shm

tmpfs                   tmpfs     7.7G   82M  7.7G    2% /run

tmpfs                   tmpfs     7.7G     0  7.7G    0% /sys/fs/cgroup

/dev/sda1               xfs      1014M  235M  780M   24% /boot

tmpfs                   tmpfs     1.6G   12K  1.6G    1% /run/user/42

tmpfs                   tmpfs     1.6G     0  1.6G    0% /run/user/1000

/dev/mapper/centos-home xfs       100G  2.6G   98G    3% /home

1 dump /home to /

xfsdump -l 0 -L boot_all -M boot_all -f /home.dump /home

2 umount /home

fuser -muv /home 

/home:               root     kernel mount (root)/home

                     amas       8367 ..c.. (amas)sftp-server

[root@amastest /]# cd /

[root@amastest /]# kill -9 8367

[root@amastest /]# umount /home

3 remove home

LVMボリューム（lv path）を非活性化する

lvchange -an /dev/mapper/centos-home

LVMボリューム（lv path）を削除する

lvremove /dev/mapper/centos-home 

4 create /home

lvcreate -L 100G -n home centos

mkfs.xfs /dev/centos/home

mount /dev/centos/home

5 restore /home

xfsrestore -f /home.dump -L boot_all /home

#空いたサイズをrootに割当

lvextend -l +100%FREE /dev/centos/root

#rootを拡張

xfs_growfs /dev/mapper/centos-root

#確認

df -Th

from http://hogem.hatenablog.com/entry/20120711/1342018292

linux LVM でextパーティションのサイズ変更(拡大/縮小)

linux

• man lvm
• man lvextend
• man lvreduce
• man resize2fs

あんましlvm使わないので勉強。実験した環境

VG Name	vg_hoge
LV Name	lv_home
LV Size	400.00 GiB
device	/dev/vg_hoge/lv_home

ext4(ext3も?)拡大はオンライン(マウントしたまま)で変更可能。縮小はアンマウントが必要。

準備

色々確認しておく

# tune2fs -l /dev/vg_hoge/lv_home
# vgs
# lvs
# lvdisplay
# df -h

縮小する (lvreduce)

400Gから300Gに変更。順番としては、まずファイルシステム上でサイズを変更してから、パーティションのサイズを変更する。

1. umount する

# umount /home

2. fsckする
これをせずにresize2fs を実行すると、"Please run 'e2fsck -f /dev/vg_hoge/lv_home' first." と怒られる。

# fsck.ext4 -f /dev/vg_hoge/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/vg_hoge/lv_home : 19/26214400 files (0.0% non-contiguous), 27910434/104857600 blocks 

3. resize2fs でファイルシステムを縮小

# resize2fs /dev/mapper/vg_svxxx-lv_home 300G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/vg_svxxx-lv_home to 78643200 (4k) blocks.
The filesystem on /dev/mapper/vg_svxxx-lv_home is now 78643200 blocks long.

4. lvreduce でパーティションを縮小

# lvreduce -L 300G /dev/vg_svxxx/lv_home
  WARNING: Reducing active logical volume to 300.00 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 300.00 GiB
  Logical volume lv_home successfully resized

5. 再マウントして確認

# mount /home
# df -h
# vgs
# lvs
# lvdisplay
# tune2fs -l /dev/vg_hoge/lv_home

拡大する (lvextend)

300Gから400Gに拡大する。拡大はオンラインのまま可能。縮小の時と順番が逆になって、パーティションを拡大してから、ファイルシステムを拡大する。

1. lvextendで拡
大する

# lvextend -L 400G /dev/vg_hoge/lv_home
Extending logical volume lv_home to 400.00 GiB
Logical volume lv_home successfully resized

2. resize2fs でファイルシステムを拡大

# resize2fs /dev/vg_hoge/lv_home 400G
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_hoge/lv_home is mounted on /home; on-line resizing required
old desc_blocks = 19, new_desc_blocks = 25
Performing an on-line resize of /dev/vg_hoge/lv_home to 104857600 (4k) blocks.
The filesystem on /dev/vg_hoge/lv_home is now 104857600 blocks long.

resize2fs 中に別のターミナルでdfしていると、sizeが徐々に拡大していくことがわかる。

3. 確認

# df -h
# vgs
# lvs
# tune2fs -l /dev/vg_hoge/lv_home

from https://www.linuxtechi.com/reduce-size-lvm-partition/

How to reduce LVM partition size in RHEL and CentOS

by Pradeep Kumar · Published April 17, 2014 · Updated August 4, 2017

Sometimes when we are running out of disk space in our Linux box and if partition created on LVM , then we can make some free space in the volume group by reducing the LVM using lvreduce command.In this article we will discuss the required steps to reduce the size of LVM safely on CentOS and RHEL Servers, Below steps are eligible when the LVM partition is formated either as ext

Scenario : Suppose we want to reduce /home by 2GB which is on LVM partition & formated as ext4.

[root@cloud ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/mapper/vg_cloud-LogVol00
                       12G   9.2G  1.9G  84%  /home

Step:1 Umount the file system

Use the beneath umount command

[root@cloud ~]# umount /home/

Step:2 check the file system for Errors using e2fsck command.

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
 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_cloud-LogVol00: 12/770640 files (0.0% non-contiguous), 2446686/3084288 blocks

Note: In the above command e2fsck , we use the option ‘-f’ to forcefully check the file system, even if the file system is clean.

Step:3 Reduce or Shrink the size of /home to desire size.

As shown in the above scenario, size of /home is 12 GB , so by reducing it by 2GB , then the size will become 10GB.

[root@cloud ~]# resize2fs /dev/mapper/vg_cloud-LogVol00 10G
 resize2fs 1.41.12 (17-May-2010)
 Resizing the filesystem on /dev/mapper/vg_cloud-LogVol00 to 2621440 (4k) blocks.
 The filesystem on /dev/mapper/vg_cloud-LogVol00 is now 2621440 blocks long.

Step:4 Now reduce the size using lvreduce command.

[root@cloud ~]# lvreduce -L 10G /dev/mapper/vg_cloud-LogVol00
 WARNING: Reducing active logical volume to 10.00 GiB
 THIS MAY DESTROY YOUR DATA (filesystem etc.)
 Do you really want to reduce LogVol00? [y/n]: y
 Reducing logical volume LogVol00 to 10.00 GiB
 Logical volume LogVol00 successfully resized

Step:5 (Optional) For the safer side, now check the reduced file system for errors

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
 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_cloud-LogVol00: 12/648960 files (0.0% non-contiguous), 2438425/2621440 blocks

Step:6 Mount the file system and verify its size.

[root@cloud ~]# mount /home/
 [root@cloud ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/mapper/vg_cloud-LogVol00
                       9.9G  9.2G  208M  98% /home