By default, most Linux Installers create separate /home partition, occupying most of the drive space.
When server is used mostly for system services, you may transfer free space from /home partition to /root.
Before adjustment we have 98% filled root partition and 141GB free space on /home, which we would like to use:
[root@oracle ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_oracle-lv_root
50G 1G 50G 98% /
tmpfs 630M 0 630M 0% /dev/shm
/dev/cciss/c0d0p1 477M 106M 346M 24% /boot
/dev/mapper/vg_oracle-lv_home
149G 60M 141G 1% /home
1. First step is to unmount /home partition
umount /home
System may refuse to unmount /home if you have users logged on to the box or services running from /home. After logging off / stopping services command should succeed.
2. Shrink old /home partition to 20GB, (system will force you to check filesystem for errors by running e2fsck)
e2fsck -f /dev/mapper/vg_oracle-lv_home resize2fs /dev/mapper/vg_oracle-lv_home 20G
3. Reduce the LVM to 20G
lvreduce -L 20G /dev/mapper/vg_oracle-lv_home
4. Extend /root LVM to new size, utilizing 100% of free space on disk
lvextend -l +100%FREE /dev/mapper/vg_oracle-lv_root
5. Grow /root (ext3/4) partition to new LVM size
resize2fs /dev/mapper/vg_oracle-lv_root
6. Mount /home
mount /home
Result
[root@oracle ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_oracle-lv_root
178G 50G 128G 28% /
tmpfs 630M 0 630M 0% /dev/shm
/dev/cciss/c0d0p1 477M 106M 346M 24% /boot
/dev/mapper/vg_oracle-lv_home
20G 45M 19G 1% /home
After these simple steps we have 72% of free disk space of root partition.
TL;DR
Resizing /home partition (/dev/mapper/vg_oracle-lv_home) to 20GB and transfering remaining space to /root (/dev/mapper/vg_oracle-lv_root):
umount /home e2fsck -f /dev/mapper/vg_oracle-lv_home resize2fs /dev/mapper/vg_oracle-lv_home 20G lvreduce -L 20G /dev/mapper/vg_oracle-lv_home lvextend -l +100%FREE /dev/mapper/vg_oracle-lv_root resize2fs /dev/mapper/vg_oracle-lv_root mount /home
Your heading “_online_ resize…” is misleading because your first
(and necessary) step is unmounting /home.
Online shrinking of LVM partitions is not possible.
I stumbled over this page because I saw “online” and “shrink”
and thought “Oooh something new I have missed something”.
🙂 Olaf
sorry for confusion, I agree it is partially online – at least you don’t need to unmount root 🙂
Firstly, thanks for the information. Worked perfect for me and now have plenty of room to store under /root folder. Probably would of been easier for me to set the partitions correctly when I installed fedora but hey no-ones perfect…
Had all sorts of trouble trying to do this on my system to start with because I was logged in.
Recommend to all to use rescue mode boot from usb/cd. This ensured no users being logged in and no files being used in /home directory. Also means you don’t have to carry out ‘lazy’ umount on /home.
Thank you very much,
just resized my filesystem with no issues.
Worked perfectly for me. Thanks for putting this up!
I cannot unmount my /home. It says “device is busy”. How do I deal with this
This is common error, try following:
1. change your directory to something not /home (cd /root)
2. check who is logged in to the box by running who, ask them to log off/ kill their pts process (ps -dN|grep pts/3)
3. if you have services running from home, stop them
perfect documents sucessfully shirnk home partition and increase root on centos 6.5
I have applied this in my Centos (2.6.32-431.29.2.el6.x86_64) server and it works fine !!
Thanks
It worked flawlessly on OEL 6.8.Thanks for the excellent tip
I closely followed the instructions, but have an issue after step 2.
I successfully (without errors) ran
e2fsck -f /dev/my_home
resize2fs /dev/my_home 426G
The initial size of /home was 436G, so I tried to reduce by about 10G. I still had about 40G free space in /home.
When I want to run
lvreduce -L 426G /dev/my_home
I obtain an error that the location does not exists. Checking with
df
shows that /dev/my_home does not exist anymore. Any idea what happened?
check dmesg for any errors