lsblk — inspect block device structure

💬 "lsblk command"

lsblk shows the disk and partition structure attached to the server in a tree. It is an essential check before adding or mounting disks.

While df shows the file system perspective, lsblk shows the device perspective.

• Concept: Displays block devices (disks, partitions, LVM volumes) and mount points in a hierarchy.
• NAME: Device name. Formats such as vda, vda1, nvme0n1p1.
• SIZE: Device capacity.
• MOUNTPOINT: Mounted path. If empty, the device is not mounted.

Commonly used options

Three essential command combinations

• lsblk -f — Check file system type and mount status
• lsblk -o NAME,SIZE,TYPE,MOUNTPOINT — View only the columns you need
• lsblk -f /dev/vdb — Check partitions/filesystems on a specific disk

💬 "Give me an example of isolating a problem server with this command"

This is a step-by-step summary of situations you often encounter on live servers.

Step 1 · Check the overall device structure

Check disks, partitions, and mount status.

lsblk -f

Step 2 · Choose a new disk

Find a device with an empty mount point.

lsblk -o NAME,SIZE,TYPE,MOUNTPOINT

Step 3 · Verify after mounting

After creating a filesystem and mounting it, check again.

lsblk -f /dev/vdb

In practice, this is how it's used

1. Adding a disk

Situation — You added a volume in the cloud, but it doesn't appear yet.

lsblk -o NAME,SIZE,TYPE,MOUNTPOINT

Result — If a new device (vdb) appears without a MOUNTPOINT, it needs to be mounted.

Point — Proceed in this order: check device → create filesystem → register in /etc/fstab.

2. Checking for missing mounts

Situation — After a reboot, /data appears empty.

lsblk -f && grep /data /etc/fstab

Result — If the device exists but is not mounted, check the fstab configuration or mount failure.

Point — For partitions not shown by df, first check with lsblk whether the device itself is recognized.

Things to watch out for

• Creating a filesystem on an unmounted device can destroy existing data. Always double-check the device name.
• In LVM environments, physical volumes and logical volumes are shown together, which can make the structure complex. Use -o to view only the items you need.
• Device names (vda/vdb) can change depending on boot order, so use UUIDs in fstab.

Actual command output

This is the result of checking disks, partitions, and mount points (including vdc, which is not mounted).

!lsblk command output: block device structure

Production server

Source (HTML): https://games.aidebatehub.com/programs/linux/filesystem/lsblk.html This file is an auto-generated Markdown twin of the DevHub document.