Mounting Filesystems

To be able to use a filesystem after creation, we need to mount it somewhere within the tree structure in a child directory within the / directory.

To be able to mount a filesystem, we first need to create a directory.

Then we can mount it.

mkdir /home/mount_point
sudo mount -t ext /dev/sdb4 /home/mount_point

This will mount a ext4 filesystem on the partition /dev/sdb4 into mount point /home/mount_point. Any files residing in /home/mount_point will be hidden until umount.

We can unmount the filesystem:

sudo umount /home/mount_point
# OR
sudo umount /dev/sdb4

This needs to be done only on filesystems not currently running/in use (device is busy).

We can create and mount a filesystem:

# Create a fs full of zeros
# read/write 1M at a time
# and copy 512 input blocks
dd if=/dev/zero of=/tmp/zeros bs=1M count=512

# Load XFS filesystem
sudo /sbin/mkfs.xfs /tmp/zeros

# OR
sudo mkfs -t xfs /tmp/zeros

# Mount the filesystem 
sudo mount /tmp/zeros /mnt

We can see that the filesystem is mounted:

lsmod | grep xfs

Module                  Size  Used by
xfs                  1204224  1

Mounting at Boot and /etc/fstab

During system initialization, the following command is executed:

mount -a

This mounts all filesystems listed in /etc/fstab configuration file. It is also popular to use autofs or automount tools to automatically mount filesystems.

Checking Filesystem for Errors

Every filesyste has a utility designed to check and fix errors. The generic name is fsck.

fsck [-t fstype] [options] [device-file] [-a] [-r]

# using -r will prompt fixing issue one by one
# using -a the issues will be fixed automatically

fsck should only be run on an unmounted filesystem.

We can use the following to force filesystem check of all mounted filesystems upon reboot:

sudo touch /forcefsck #file will dissappear after a successful check.
sudo reboot