How to Expand a Linux Disk from 500GB to 2TB Without Data Loss

Disk expansion procedure

Assume a virtual disk /dev/vdc has been enlarged from 500 GB to 2 TB and the existing partition vdc1 must be expanded to use the new space.

Identify partition start

fdisk -l /dev/vdc

Record the start sector (e.g., 2048). The same start value must be used when recreating the partition.

Unmount and delete the partition

umount /data

Launch the partition editor without writing changes:

fdisk /dev/vdc
d   # delete partition 1
# do NOT write (w) or quit (q) yet

Recreate the partition with the same start

fdisk /dev/vdc
n   # new primary partition
1   # partition number
2048   # start sector (same as recorded)
<em>Enter</em>   # accept default end sector to use the whole disk or specify a larger last sector (e.g., 4194303999)
w   # write table and exit

Resize the filesystem

For an ext4 filesystem:

e2fsck -f /dev/vdc1
resize2fs /dev/vdc1

Remount and verify

mount /dev/vdc1 /data
lsblk
df -h

General partitioning commands

fdisk -l

– list disks and partitions. fdisk /dev/<em>device</em> – interactive MBR partition editor (supports up to 2 TB). mkfs.ext4 /dev/<em>partition</em> – create an ext4 filesystem. mount /dev/<em>partition</em> /mountpoint – mount a filesystem. df -h – display disk usage.

Automatic mounting options

/etc/fstab

Add a line such as:

/dev/vdc1   /data   ext4   defaults,nofail   0   2

/etc/rc.local

Append the mount command so it runs at boot:

mount /dev/vdc1 /data

systemd mount unit

Create /etc/systemd/system/mnt-volume.mount with the following content:

[Unit]
Description=Mount DO Volume volume

[Mount]
What=/dev/disk/by-uuid/d946870c-ef31-48ee-a9f1-446acaa56f46
Where=/mnt/volume
Options=defaults,nofail,discard,noatime
Type=ext4

[Install]
WantedBy=multi-user.target

Enable and control the unit:

systemctl enable mnt-volume.mount
systemctl start mnt-volume.mount
systemctl status mnt-volume.mount
systemctl stop mnt-volume.mount
systemctl disable mnt-volume.mount

autofs

Install the daemon and configure on‑demand mounting: yum install -y autofs Further configuration is outside the scope of this summary.

Troubleshooting common errors

Read‑only (write‑protected) mount

Reformat the partition and remount:

mkfs.ext4 /dev/sdb1
mount /dev/sdb1 /data

Superblock read error

Run a low‑level filesystem check and then remount:

fsck.ext3 -B 1024 /dev/vdb
mount /dev/vdb /data

Additional notes

The partition must be deleted and recreated with the identical start sector; data remains intact because the filesystem is not overwritten.

Stop services that use the filesystem (e.g., MySQL, Elasticsearch) before resizing to avoid corruption.

For XFS filesystems use xfs_growfs /mountpoint instead of resize2fs.

If the disk is managed by LVM, use pvresize, lvextend, and the appropriate filesystem resize tool.