How to Check File System Block Size in Ubuntu

This article provides a concise guide on identifying the block size of a file system within the Ubuntu operating system. Knowing the block size is crucial for system administration tasks involving disk optimization and storage management. Below, you will find the specific terminal commands required to retrieve this information accurately and efficiently.

The Stat Command

The primary command to show the block size of a mounted file system is stat. Execute the following in your terminal:

stat -f /

In the output, find the IO Block size line. This number represents the file system block size in bytes.

The Tune2fs Command

For ext2, ext3, or ext4 partitions, use tune2fs to read the superblock information. This requires root access:

sudo tune2fs -l /dev/sda1 | grep "Block size"

Replace /dev/sda1 with your specific partition path. This displays the configured block size directly from the file system metadata.

The Blockdev Command

You can also use blockdev to query the kernel for the block size. Run this command with your device path:

sudo blockdev --getbsz /dev/sda1

This returns only the numeric value of the block size, making it ideal for scripts or quick checks.