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I made a mistake in setting up one of our XenServer-based Linux VMs. I created a separate swap (good) and a large separate /home directory (bad) when really it should have been a large separate /var directory instead.

Now that /var has almost saturated the root disk, I would like to reintegrate /home back into the root partition, delete the old 921GB /home partition, then grow the root partition to 921GB leaving the /swap partition untouched.

Currently:

[root@ /]# df -h

Filesystem                       Size  Used Avail Use% Mounted on 
/dev/mapper/VolGroup-lv_root      50G   43G  4.0G  92% / 
tmpfs                            3.9G     0  3.9G   0% 
/dev/shm /dev/xvda1              485M   72M  388M  16% /boot 
/dev/mapper/VolGroup-lv_home     921G  200M  874G   1% /home

So more clearly, I need to know how to move /home and it's contents to the root partition (/dev/mapper/VolGroup-lv_root) and have Linux recognize it as the OS's home directory, delete the /dev/mapper/VolGroup-lv_home partition, and then grow the /dev/mapper/VolGroup-lv_root partition to take up the additional 921GB available.

I'm open to swapping /home and /var's locations if possible, but this is a production server. I can make instant snapshots at will though, so some late night experimentation is possible! ;)

Thanks!

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3 Answers 3

up vote 3 down vote accepted

It's fairly straightforward, as root:

mkdir /home2
mv /home/* /home2/
umount -fl /home
lvremove /dev/VolGroup/lv_home
mv /home2 /home
  • edit your fstab and remove the entry for /dev/VolGroup/lv_home
  • check how much space you now have available in VolGroup with vgdisplay and add that much to lv_root with lvextend
  • use resize2fs or xfs_growfs as appropriate on lv_root
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Thanks very much, however I get "Logical volume VolGroup/lv_home contains a filesystem in use." Did I need to do this in single user mode? –  stet Jul 20 '13 at 15:32
    
I mixed answers below and rebooted with the /home commented out of fstab and then removed it. Thanks. –  stet Jul 20 '13 at 17:51

You could also do this without growing the partition by just swapping the mount points:

unmount the home partition:

umount /home

mount it somewhere else, e.g. to /mnt:

mount /dev/mapper/VolGroup-lv_home /mnt

move everything from the partition to your home directory (which is on the root partition now):

mv /mnt/* /home/

move the data from your /var directory to the partition:

mv /var/* /mnt/

remount your partition to /var:

umount /mnt

mount /dev/mapper/VolGroup-lv_home /var

Make sure to change the contents of your /etc/fstab afterwards accordingly.

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Will this move the files that are held open by daemons correctly or will they continue to be written to the original ? –  Iain Jul 20 '13 at 15:13
    
I'd suggest to stop any services accessing /var beforehand and start them again afterwards. Between the steps of moving the data from /var/ to /mnt and remounting to /var/, the /var directory will be empty so anything accessing it won't work anyway. –  etagenklo Jul 20 '13 at 15:44

This process will work if your root filesystem is resizeable (ext4 for example).

  1. modify a existing user or create a new user whose home directory is not under /home.
  2. verify that you can login as that user and su to root
  3. ensure all other users are logged out
  4. umount /home - if this fails then user processes may still be using /home. Check with fuser or lsof
  5. remount /dev/mapper/VolGroup-lv_home on a temporary mount - /mnt/home for example
  6. use rsync, cp -p or some other tool to copy the user home directories from /mnt/home to /home - verify that the permissions and ownerships are correct
  7. edit fstab to comment out /home
  8. users can now be allow to log back in
  9. lvremove /dev/VolGroup/lv_home
  10. lvextend -L+921G /dev/VolGroup/lv_root
  11. resize2fs /dev/VolGroup/lv_root
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Thank you for the clarifications in steps 10 and 11! I hope people vote up this answer. –  stet Jul 20 '13 at 17:51

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