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mount disk image created with dd using ubuntu

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If you’ve cloned a whole drive using dd and you need to access one of the partitions on it here are some steps to follow in order to gain access:

Find the partition start sectors using fdisk -b512 -l. Note that you’re explicitly setting the sector size to 512 bytes and you’ll need to change your command to match your own image file.

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fdisk -b512 -l backup_sata.img

You should get output similar to this (note I’ve truncated it to only show the appropriate output):

Shell
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Device         Boot     Start       End   Sectors   Size Id Type
backup_sata.img1 *         2048    206847    204800   100M  7 HPFS/NTFS/exFAT
backup_sata.img2         206848 237185023 236978176   113G  7 HPFS/NTFS/exFAT
backup_sata.img3      237185024 588070911 350885888 167.3G  f W95 Ext'd (LBA)
backup_sata.img4      588070912 625137663  37066752  17.7G 27 Hidden NTFS WinRE
backup_sata.img5      237187072 588070911 350883840 167.3G  7 HPFS/NTFS/exFAT

Normally sector are 512 bytes, so you can calculate the offset you need in the next command with:

start * 512 = offset

So if you want to mount backup_sata.img5 (partition 5 of the backup image) you’d run 237187072×512=121439780864:

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mount -o ro,loop,offset=121439780864 backup_sata.img /backup_sata

Remember to have created /backup_sata or whatever directory you’re mounting to first!

Checking a hard drive’s SMART status from the Linux command line

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SMART (Self-Monitoring Analysis and Reporting Technology) allows you to gather and assess if a hard drive has or is near failure. On Debian and Ubuntu based systems (including both flavors of Mint) the smartmontools package contains everything you need to check your drives.

It’s usually a good idea to make sure your Linux distrobution’s repositories are up to date:

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sudo apt-get update

Start by installing the smartmontools package to give you access to the utilities to check your hard drive from the command line:

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sudo apt-get install smartmontools

Once the package is installed, you can start checking your hard drives. It’s a good idea to run a short test first. To do this type the command below, replacing /dev/sda with your hard drive.

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smartctl --test=short /dev/sda

The command will tell you how long it is going to take to test the drive. Normally this is only a few minutes for a short test but can be hours for a longer one:

=== START OF OFFLINE IMMEDIATE AND SELF-TEST SECTION ===
Sending command: “Execute SMART Short self-test routine immediately in off-line mode”.
Drive command “Execute SMART Short self-test routine immediately in off-line mode” successful.
Testing has begun.
Please wait 2 minutes for test to complete.

Once you’ve waited for the drive test to finish you can check the health status of your hard drive. Your first option is a summary telling you if it’s passed or failed:

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smartctl -H /dev/sda

If you want more information on the status of your hard drive you can run the following command:

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smartctl -a /dev/sda

In the event you find anything you’d consider to be suspicious or your hard drive has been acting strangely you can run a longer test, but this usually takes a few hours to complete:

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smartctl --test=long /dev/sda

It’s important to note that a SMART test is only one indication of a failing hard drive. You could test a drive and it pass but still fail the following day. Clicking noises are a good indication of a hard drive that has or is about to fail. You should always have a good backup of all of your data. If your hard drive does fail your disk provider may have tools available on their website to allow you to check them or require you to provide information for an RMA.