blockdev - Linux

Overview

blockdev is a versatile Linux utility that allows users to manage, query, and manipulate block devices. It provides a comprehensive suite of features for working with storage devices such as hard disks, SSDs, and USB drives.

Syntax

blockdev [options] <device> <command> [arguments]

Options/Flags

  • -h, –help: Display the help message
  • -v, –version: Display the version information
  • -g : Set the block size of the device
  • -o : Set the offset (in bytes) within the device
  • -p : Set the number of blocks to operate on
  • -r: Rotate the data in the device by a specified number of bytes
  • -s: Show the size of the device
  • -f: Force the operation to complete even if it results in data loss
  • -i: Ignore errors and continue the operation

Examples

  • Get the size of a device:
blockdev --getsize /dev/sda
  • Set the block size of a device:
blockdev --setsize 4096 /dev/sdb
  • Rotate the data in a device by 512 bytes:
blockdev --rotate 512 /dev/sdc
  • Zero out a device:
blockdev --zerofill /dev/sdd

Common Issues

  • Device not found: Ensure that the specified device is connected to the system and is correctly identified.
  • Permission denied: Ensure that you have sufficient permissions to perform the operation.
  • Invalid command: Check that the specified command is valid and supported by blockdev.

Integration

blockdev can be integrated with other commands and tools to perform complex tasks, such as:

  • Create a RAID array:
blockdev --prepare raid1 /dev/sda /dev/sdb
mdadm --create --level=1 --raid-devices=2 /dev/md0 /dev/sda /dev/sdb
  • Mount a disk image:
blockdev --setro /dev/loop0
mount /dev/loop0 /mnt

Related Commands

  • fdisk: Partition and manage disk drives
  • mkfs: Create filesystems on block devices
  • dd: Copy and convert block devices
  • lsblk: List block devices and their properties