How to Join Several Partitions on Linux

In this article, we will create a single partition on Linux using 2 drives of 20 GB each to make a 40 GB single mount point so that we can store the data in one place with more space on the volume. Here, we are using a package called ‘mhddfs‘ which is a driver for Linux that combines several mount points into a virtual disk. This is a fuse based driver which provides an easy solution for large data storage that combines many small file systems into a single big virtual file system.

Features of Mhddfs

• We can get System information and file system attributes.
• It can set attributes of the filesystem.
• Files and Directories can be Created, Read, Removed and Written.
• Supports hard links and file locks on a single device.

Advantages

• Very friendly for home users.
• Easy and simple to use.
• No Data loss.
• Files are not split into multiple hard disks.

Dis-Advantages

• No inbuilt drivers for Linux.
• Requires lot of processing of power during runtime.
• Hard-links moving will not be supported.
• No redundancy solution.

Installation of Mhddfs in Linux

Before proceeding further, please note that installation is needed to be a root user

# sudo -i

Execute the below command to install ‘mhddfs’ package.

# apt-get install mhddfs
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
mhddfs
0 upgraded, 1 newly installed, 0 to remove and 64 not upgraded.
Need to get 0 B/26.0 kB of archives.
After this operation, 96.3 kB of additional disk space will be used.
Selecting previously unselected package mhddfs.
(Reading database ... 91977 files and directories currently installed.)
Preparing to unpack .../mhddfs_0.1.39+nmu1ubuntu1_amd64.deb ...
Unpacking mhddfs (0.1.39+nmu1ubuntu1) ...
Processing triggers for man-db (2.7.4-1) ...
Setting up mhddfs (0.1.39+nmu1ubuntu1) ...
# df -h
Filesystem Size Used Avail Use% Mounted on
udev 473M 0 473M 0% /dev
tmpfs 98M 4.9M 93M 5% /run
/dev/dm-0 19G 3.1G 15G 18% /
tmpfs 488M 0 488M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 488M 0 488M 0% /sys/fs/cgroup
/dev/sda1 236M 51M 173M 23% /boot
tmpfs 98M 0 98M 0% /run/user/1000
/dev/sdb1 20G 44M 19G 1% /backup
/dev/sdc1 20G 44M 19G 1% /backup1

Take a note of the mount point’s name from output, which we will be using later in next steps.

Create a directory /mnt/virtual HDD where these file system will be grouped together and mounted.

# mkdir /mnt/virtualhdd

Then we needed to mount the /backup and /backup1. We need root permissions to who is a member of FUSE group.

# mhddfs /backup,/backup1 /virtualhdd/ -o allow_other
mhddfs: directory '/backup' added to list
mhddfs: directory '/backup1' added to list
mhddfs: mount to: /virtualhdd/
mhddfs: move size limit 4294967296 bytes

We used the mount point names of all the HDDs. Obviously, the mount point in your case will be different. Also, notice “-o allow_other” is used to make Virtual file system to be visible to all other users who using this Linux system.

Now run “df -h” see all the disks and mount points which we created.

# df -l
Filesystem 1K-blocks Used Available Use% Mounted on
udev 483472 0 483472 0% /dev
tmpfs 99888 4972 94916 5% /run
/dev/dm-0 19213004 3158668 15055324 18% /
tmpfs 499420 0 499420 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 499420 0 499420 0% /sys/fs/cgroup
/dev/sda1 240972 51472 177059 23% /boot
tmpfs 99888 0 99888 0% /run/user/1000
/dev/sdb1 20504628 44992 19395016 1% /backup
/dev/sdc1 20504628 44992 19395016 1% /backup1
/backup;/backup1 41009256 89984 38790032 1% /virtualhdd

For automatic creation of Virtual File system to boot every time, we should add the below line at the end of /etc/fstab.

# vi /etc/fstab
# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
/dev/mapper/server--vg-root / ext4 errors=remount-ro 0 1
# /boot was on /dev/sda1 during installation
UUID=40f8b7fe-3195-414a-a0e4-a4443cceb78c /boot ext2 defaults 0 2
/dev/mapper/server--vg-swap_1 none swap sw 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto,exec,utf8 0 0
mhddfs /backup,/backup1 /virtualhdd/ -o allow_other fuse defaults allow_other 0 0

Unmount the Virtual Drive

# umount /mnt/virtualhdd

After this configuration using ‘mhddfs’ utility it made very simple to combine different hard disks into a single storage. The best thing is that it is very easy to set up and we never lose data in this filesystem. If you have a larger data, then the disk you have and needed to save date in a single point, then we can your is setup and configured such that we can save that big or huge data.