Complete Guide to Mounting a Data Disk on CentOS/Linux Server

Complete Guide to Mounting a Data Disk on CentOS/Linux Server

After logging into your CentOS server via SSH, follow these steps to mount a data disk.

Important Warning: Mounting operations (especially formatting) will erase all data on the target disk. Ensure the target disk (e.g., /dev/vdb) contains no important data or is not in use.

Step 1: Identify the Disk Device

First, identify the device name of the newly added data disk.

lsblk
# or
fdisk -l

Tip: The system disk is often /dev/vda or /dev/sda. A new data disk might be /dev/vdb, /dev/sdb, etc. Identify it carefully by size; do not mistake it for the system disk. Use df -h to see mounted system disks for exclusion.

Step 2: Partition the Disk

Assuming the data disk is /dev/vdb, use fdisk to create a partition.

fdisk /dev/vdb

In the interactive interface, enter these commands sequentially (# denotes comments, do not type):

n    # new partition
p    # primary partition
1    # partition number (default 1)
     # first sector (press Enter for default)
     # last sector (press Enter to use entire disk)
w    # write and exit

After this, you'll have a new partition: /dev/vdb1.

Step 3: Format the Partition

Format the new partition with the ext4 filesystem (common for Linux).

mkfs.ext4 /dev/vdb1

Formatting may take a few seconds.

Step 4: Mount the Partition

Mount the formatted partition to a system directory.

# 1. Create a mount point, e.g., /data
mkdir /data

# 2. Mount the partition
mount /dev/vdb1 /data

# 3. Verify the mount
mount | grep /data

If the output shows /dev/vdb1 mounted at /data, the mount succeeded.

Step 5: Configure Automatic Mount at Boot

Manual mounts are lost after reboot. Add an entry to /etc/fstab for automatic mounting.

# Append the configuration to fstab
echo '/dev/vdb1   /data   ext4    defaults  0 0' >> /etc/fstab

Configuration breakdown:

• /dev/vdb1: Device/partition to mount.
• /data: Mount point directory.
• ext4: Filesystem type.
• defaults: Mount options (rw, suid, dev, exec, auto, nouser, async).
• 0: First 0: no dump backup.
• 0: Second 0: no filesystem check at boot (root is usually 1).

Finally, verify the configuration and test it:

# Check fstab content
cat /etc/fstab

# Test fstab syntax (does not actually mount)
mount -a

# Verify the mount is present
df -h | grep /data

If mount -a produces no errors and df -h shows /data, the configuration is successful. The data disk will mount automatically at /data on the next reboot.