How to move /home directory into a ZFS pool on Linux Mint 19XFCE-64bit
Reference: https://freedompenguin.com/articles/how-to/move-linux-home-zfs/
This procedure has been tested on a guest Linux Mint 19XFCE 64bit inside VirtualBox V5.2.22
Host system Linux Mint 18 KDE 64 bit
Anything described below refers to the guest OS.
Procedure is not 100% step by step. Some steps are described giving their gobal meaning, not
going in deep details.
Every time it will be mentioned the word “user” it means YOUR user directory name (for example instead of /home/user/Documents put /home/jonathan/Documents where jonathan is an example name)
Following procedure is valid for one single user.
Last, but not less important, forgive my english. I am italian.
Procedure
installation of zfs utils by terminal
sudo apt install zfsutils-linux
By using G-Parted:
Reduce the only available partition to a reasonable value (let’s say 20-25 Gbyte).
On free space created by previous step, create a new partition NOT formatted.
By file browser, go to /dev/disk/by-id/ and take note of second partition name. Such partition is that one just created (NOT formatted) that will host ZFS pool dedicated to /home directory.
In my case, second partition name was ata-VBOX_HARDDISK_VB49b2d698-41fa84b3-part2
You will see such name in the pool creation sintax here below.
Now we create the zhome pool using the partition 2 NOT formatted we just created.
By terminal
zp=zhome
sudo zpool create -o ashift=12 -o autoexpand=on -o autoreplace=on -O atime=off -O compression=lz4 $zp /dev/disk/by-id/ata-VBOX_HARDDISK_VB49b2d698-41fa84b3-part2
The detailed meaning of different parameters can be found in the reference article mentioned at the beginning.
Now we must backup directory /home/user/ into a temporary directory such as /tmp/user-bck/
By terminal
sudo rsync -avh /home/user/ /tmp/user-bck/
Now we must erase directory /home
I don’t know why, but command must be given twice to succeed (first time it warns "directory is not empty"...)
By terminal
sudo rm -r -f /home
sudo rm -r -f /home
SOME NOTES
1)
it is a good thing having ZFS Datasets instead of IMPORTANT directories.
That because it will allow to take selective snapshots SPECIFIC for each directory.
VERY useful, just to mention, in case of Each virtual machine directory...
2)
Each dataset is seen by file browser as a NORMAL directory.
So, inside of it, we can then create whatever subdirectories we want.
BUT IT IS FORBIDDEN to create a ZFS Dataset in this way: pool/dataset1/directory/dataset2
3) Snapshots apply to datasets only, NOT to directories…
Now let’s create EVERY ZFS Datasets with EXACTLY the same name as /home/user directories (Documents, Music, etc.) Be carefull: I translated the names of directories from italian to english. Please, make sure of the sintax (Documents, Pictures, Music, etc.)
By terminal
sudo zfs create -o sharesmb=off $zp/home
sudo zfs create $zp/home/user
sudo zfs create $zp/home/user/Documents
sudo zfs create $zp/home/user/Pictures
sudo zfs create $zp/home/user/Music
sudo zfs create $zp/home/user/Video
sudo zfs create $zp/home/user/Models
sudo zfs create $zp/home/user/Download
sudo zfs create $zp/home/user/Desktop
Now we give (immediate and permanent) instruction to ZFS about mount point of the pool zhome/home.
Mount is performed immediately and will be performed on every boot.
By terminal
sudo zfs set mountpoint=/home $zp/home
Now we must restore /home/user backup and place it into the new, EMPTY, just mounted, /home directory.
By terminal
cd /
sudo rsync -avh --ignore-existing /tmp/user-bck/ /home/user/
Option –ignore-existing is given to avoid overwriting of directories on the same-name ZFS Datasets (Documents, Music, etc.)
Now reboot system
By terminal
sudo reboot
Tested on 21 Novembre 2018 ore 22:30.
Regards
Michele
