To reduce / extend LV on SuSE / Red Hat Linux

Steps to reduce /home file system:

1. Take backup of Filesystem before going to start LV reduce activity

For example if you want to reduce /home file system
# mkdir /var/tmp-bkp-home   <-- to make temporary folder for backup as per disk space availability
# cd /var/tmp-bkp-home
# tar -cf home-bkp-7th-July-2015.tar /home
# ls -lh home-bkp-7th-July-2015.tar


2. Take pre-check before starting the activity
# df -h /home
# vgdisplay VolGroup00
# lvdisplay /dev/VolGroup00/LogVol03 <-- is for /home file system


3. Unmount the /home file system
# umount /home
umount: /home: device is busy
umount: /home: device is busy

If get device busy error check user/process that is still using file system
 # lsof /home
# fuser -cu /home
/home:               24551c(sharmaxx) 26948c(root)
# fuser -ck /home
/home:               24551c 26948c
Hangup

Kill process to release the /home file system

# kill -9 24551
# kill -9 26948

Check "open" option in lvdisplay command
# lvdisplay /dev/VolGroup00/LogVol03
    # open           0   <-- it should be zero means this LV is free to unmount

if still facing issue REBOOT is one more option if file is locked by any process or try,
# umount -f /usr/local/nete
# umount -l /usr/local/nete
# umount -lf /usr/local/nete

Make confirmation by running
# df -h /home

4. Run e2fsck to check file system
# e2fsck -f /dev/mapper/VolGroup00-LogVol03

5. Suppose size of /home is 14 GB and you want to reduce it by 4GB, then the new size will be 10GB
for than run below command:
# resize2fs /dev/mapper/VolGroup00-LogVol03 10g

6. Run LV reduce command
lvreduce -L 10GB /dev/mapper/VolGroup00-LogVol03

7. Again Run e2fsck to check file system
e2fsck -f /dev/mapper/VolGroup00-LogVol03

8. Check size of lv and vg
# vgdisplay VolGroup00
# lvdisplay /dev/VolGroup00/LogVol03 <-- is for /home file system

9. Mount file system
# mount /home

10. Finaly check file system
# df -hT /home




Steps to extend /root File System

1. Take pre-check before scanning the disk:
# vgdisplay VolGroup00
# lvdisplay /dev/VolGroup00/LogVol00
# lsscsi
# lsblk
# blkid

2. Scan new disk:
# echo "- - -" > /sys/class/scsi_host/host0/scan
# echo "- - -" > /sys/class/scsi_host/host1/scan

Alternativily you can also scan / rescan by
# ls /sys/class/scsi_host/ | while read host ; do echo "- - -" > /sys/class/scsi_host/$host/scan ; done

2. Check newly added disk:
# lsscsi
# lsblk
# blkid
# ls -lhtr /dev/disk/by-path/

3. Suppose you got new disk like /dev/sdn then, create PV:
# pvcreate /dev/sdn

4. Extend VG:
# vgextend VolGroup00 /dev/sdn

5. Extend LV:
# lvextend -L +50G /dev/VolGroup00/LogVol00

6. Run resize2fs command to resize LV online:
# resize2fs /dev/VolGroup00/LogVol00

Note : resize2fs also work for ext4 file system

For older version of Linux OS you can resize file system by
# ext2online /dev/VolGroup00/LogVol00

7. Check VG, LV and file system size:
# vgdisplay VolGroup00
# lvdisplay /dev/VolGroup00/LogVol00
# df -hT /root