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GoingMyWay
Asked: 2016-04-22 01:24:22 +0800 CST

How to shrink /home and add more space on CentOS7

  • 772

CentOS 7 file system is XFS, And resize2fs doesn't work. I need to shrink /home to 400G and add 100G space to /. What should I do?

# df -h
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   50G   50G  341M 100% /
devtmpfs                 7.8G     0  7.8G   0% /dev
tmpfs                    7.8G   84K  7.8G   1% /dev/shm
tmpfs                    7.8G  778M  7.0G  10% /run
tmpfs                    7.8G     0  7.8G   0% /sys/fs/cgroup
/dev/sda1                497M  241M  257M  49% /boot
tmpfs                    1.6G   16K  1.6G   1% /run/user/42
tmpfs                    1.6G     0  1.6G   0% /run/user/0
/dev/mapper/centos-home  500G   20G  480G   4% /home

The output of lvs, vgs and pvs are:

[root@localhost]~# lvs -v
    Using logical volume(s) on command line.
  LV   VG     #Seg Attr       LSize   Maj Min KMaj KMin Pool Origin Data%  Meta%  Move Cpy%Sync Log Convert LV UUID                                LProfile
  home centos    1 -wi-ao---- 499.38g  -1  -1  253    2                                                     4I53D9-7VSm-HN9H-QsSp-FvFU-5R9D-y5VwsN         
  root centos    1 -wi-ao----  50.00g  -1  -1  253    0                                                     LGRoEL-0EHz-G135-p6vx-Lt2s-RvI5-qdT9Sm         
  swap centos    1 -wi-ao----   7.81g  -1  -1  253    1                                                     UYB5xP-cEyV-lWvn-blIq-8s13-9kVB-ykjIWI         
[root@localhost]~# vgs -v
    Using volume group(s) on command line.
  VG     Attr   Ext   #PV #LV #SN VSize   VFree  VG UUID                                VProfile
  centos wz--n- 4.00m   1   3   0 557.26g 64.00m Gd5c08-ujdQ-fsix-o7z6-Wfsv-C0uW-XzDois         
[root@localhost]~# pvs -v
    Using physical volume(s) on command line.
    Found same device /dev/sda2 with same pvid TCmreQr93apETNoTl8bMc54l57FZ5hut
  PV         VG     Fmt  Attr PSize   PFree  DevSize PV UUID                               
  /dev/sda2  centos lvm2 a--  557.26g 64.00m 557.26g TCmreQ-r93a-pETN-oTl8-bMc5-4l57-FZ5hut
[root@localhost]~#
centos partition xfs centos7

5 Answers

  1. Best Answer

    As others have pointed out, XFS filesystem cannot be shrunk.

    So your best bet is to backup /home, remove and recreate its volume in a smaller size and give the rest to your /root volume just as Koen van der Rijt outlined in his post.

    • backup the contents of /home

    tar -czvf /root/home.tgz -C /home .

    • test the backup

    tar -tvf /root/home.tgz

    • unmount home

    umount /dev/mapper/centos-home

    • remove the home logical volume

    lvremove /dev/mapper/centos-home

    • recreate a new 400GB logical volume for /home, format and mount it

    lvcreate -L 400GB -n home centos
mkfs.xfs /dev/centos/home
mount /dev/mapper/centos-home

    • extend your /root volume with ALL of the remaining space and resize (-r) the file system while doing so

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

    • restore your backup

    tar -xzvf /root/home.tgz -C /home

    • check /etc/fstab for any mapping of /home volume. IF it is using UUID you should update the UUID portion. (Since we created a new volume, UUID has changed)

    That's it.

    Hope this helps.

    Kindly add this to sync the changes:

    dracut --regenerate-all --force

    • 71

  2. An addition to Ari's answer as I was unable to ssh using public key authentication after following his instructions.

    With selinux enabled you may get this message in /var/log/messages (with debug enabled in sshd_config) because /home was recreated:

    SELinux is preventing /usr/sbin/sshd from read access on the file authorized_keys

    Fix it by:

    restorecon -R -v /home
    • 6

  3. You can't shrink an XFS filesystem.
    You can only grow them with xfs_growfs.

    See: https://access.redhat.com/solutions/540013
    and
    https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/xfsgrow.html

    It is currently not possible to reduce the size of a partition or logical volume with the xfs filesystem. As a possible workaround in some environments, thin provisioned LVM volumes can be considered as an additional layer below the XFS filesystem.

    Find out what's taking so much space under / and split it out as its own filesystem.

    • 4

  4. you can only do this on a live system if it is partitioned with LVM - logical volume management. what is the output of:

    lvs -v
vgs -v
pvs -v
    • 0

  5. The first thing you need to do is check what has used up all your free disk space otherwise this problem will occur again sometime in the future.

    If u really need to resize my approach would be:

    • backup the contents of /home. (its only 20g)
    • umount /home
    • destroy the home logical volume (lvremove)
    • allocate space as needed, resize the volumes. (lvextend, resize2fs)
    • recreate a new logical volume for /home, format and mount it (lvcreate, mkfs.xfs)
    • restore backup
    • double check the contents of /etc/fstab that you will mount the correct volume for /home
    • run mount -a or reboot
    • 0