Skip to main content

Backup Harddisk Using the dd Command



Overview

The dd command is a useful tool for copying one entire hard drive to another. This can be helpful if you want to move your entire computer system to a new hard drive. The trick is making sure you know which drive you are copying from and which drive you are copying to. There is no recovering your data if you accidentally copy an empty drive to your system drive. It will overwrite all your information.


The Process

Here are some commands and tools that you will want to use:
  • df -h  (this will show you your drives and the disk free space)
  • dd if=/dev/sdb of=/dev/sdc (important: sdb and sdc are examples you will need to know what your specific drives are )

We can also use dd to create image backup of a hard disk
Instead of taking a backup of the hard disk, you can create an image file of the hard disk and save it in other storage devices.There are many advantages to backing up your data to a disk image, one being the ease of use. This method is typically faster than other types of backups, enabling you to quickly restore data following an unexpected catastrophe.

  # dd if=/dev/hda of=~/hdadisk.img

The above creates the image of a harddisk /dev/hda

Restore:

To restore a hard disk with the image file of an another hard disk, use the following dd command example.
  # dd if=hdadisk.img of=/dev/hdb
The image file hdadisk.img file, is the image of a /dev/hda, so the above command will restore the image of /dev/hda to /dev/hdb.

Backup a Partition

You can use the device name of a partition in the input file, and in the output either you can specify your target path or image file as shown in the dd command example below.
  # dd if=/dev/hda1 of=~/partition1.img

CDROM Backup

dd command allows you to create an iso file from a source file. So we can insert the CD and enter dd command to create an iso file of a CD content.
# dd if=/dev/cdrom of=tgsservice.iso bs=2048
dd command reads one block of input and process it and writes it into an output file. You can specify the block size for input and output file. In the above dd command example, the parameter “bs” specifies the block size for the both the input and output file. So dd uses 2048bytes as a block size in the above command.
Note: If CD is auto mounted, before creating an iso image using dd command, its always good if you unmount the CD device to avoid any unnecessary access to the CD ROM.

Comments

Popular posts from this blog

CentOS / Redhat : Configure CentOS as a Software Router with two interfaces

Linux can be easily configured to share an internet connection using iptables. All you need to have is, two network interface cards as follows: a) Your internal (LAN) network connected via eth0 with static ip address 192.168.0.1 b) Your external WAN) network is connected via eth1 with static ip address 10.10.10.1  ( public IP provided by ISP ) Please note that interface eth1 may have public IP address or IP assigned by ISP. eth1 may be connected to a dedicated DSL / ADSL / WAN / Cable router: Step # 1: Enable Packet Forwarding Login as the root user. Open /etc/sysctl.conf file # vi /etc/sysctl.conf Add the following line to enable packet forwarding for IPv4: net.ipv4.conf.default.forwarding=1 Save and close the file. Restart networking: # service network restart Step # 2: Enable IP masquerading In Linux networking, Network Address Translation (NAT) or Network Masquerading (IP Masquerading) is a technique of transceivin

Virtual Box and Alt/Tab Keys

I use virtual box for all my testing activities. It comes too often that I have a virtual box VM window open & I want to switch to my host machine to see some stuff like tutorials etc.. If you press the alt+tab combination it just works inside the VM & doesn't switches to host machine. In these scenarios you can press the host key once ( not hold it ) & then whatever you press goes to host machine. So in general where host key is the default Right Ctrl, just press Right Ctrl once & now press the alt+tab & it will switch you out to host machine. This is really helpful when you have the VM windows open or you're working on seamless mode. Hope it help others too.

Shell Script: Find Number Of Arguments Passed

Many times , when we create shell scripts we try to do repetitive tasks through functions. Some functions take arguments & we have to check the no. of arguments that are passed to it. Each bash shell function has the following set of shell variables: [a] All function parameters or arguments can be accessed via  $1, $2, $3,..., $N . [b]  $*  or  $@  holds all parameters or arguments passed to the function. [c]  $#  holds the number of positional parameters passed to the function. [d] An array variable called  FUNCNAME  ontains the names of all shell functions currently in the execution call stack. Example Create a shell script as follows: #!/bin/bash # Purpose: Demo bash function # -----------------------------   ## Define a function called test() test(){   echo "Function name:  ${FUNCNAME}"   echo "The number of positional parameter : $#"   echo "All parameters or arguments passed to the function: '$@'"   e