How do I know if an image I've created of my machine is accurate and complete?

Question

I created an image of my machine (using Clonezilla) so that I could put a new operating system onto my machine and still have everything backed up.

How can I tell if the clone was accurate and complete?

Answer 1

There's at least two scenarios you should consider for your verifying your backup image.

Successful Restore

If your true focus is to restore successfully when the worst happens; then should be more concerned with ensuring you can restore completely from that image, because until you actually simulate that your drive did fail and you need to fully recover, your backup isn't trustworthy enough.

When you successfully restore from your backup, you can "smoke test" a variety of applications and files, perform file searches, open media, save changes, then and only then can you have confidence in the image you created.

What's important:

• Up to date complete backups
• A tested and practiced recovery procedure

Quoting some good backup blog posts:

The rule of thumb is that backups ALWAYS succeed. It's restores that fail!

File/State Snapshot

But if it's just to snapshot some files and settings then as (per the other answers)

• You can use the cloning program to verify the clone worked
• Mount and extract files (link thank's to Chris Thompson's answer).

More links:

CodingHorror - What's your backup strategy

CodingHorror - International Backup Awareness Day

Scott Hanselman - The Case of the Failing Disk Drive or Windows Home Server Saved My Marriage

Answer 2

Typically, the cloning program will have an option to verify the image/backup when you create it.

Answer 3

Assuming that you're using the image taken as a way to go back and grab files that you may have missed in your standard backup, you can extract files from the archive. Following the steps to mount and extract files from the archive will, in essense, also verify that the archive is valid without corruption issues.

Some suggested methods for extracting from Clonezilla files can be found here.