Whenever there’s discussion about the difference between a clone and an image, confusion between the two terms abounds. For the most part, this confusion is warranted—both are information technology tactics for copying the complete content of a hard drive. Both create an exact or near exact record of your drive. And you can use both to back up a drive or replace an old, corrupted, or failed drive with a new—hopefully faster and larger—one.
However, it’s important to note neither involves simply copying and pasting data onto another drive. Imaging and cloning do involve the replication of files—but they also replicate boot and partition information, the allocation table, and additional data used by the operating system to locate and access the replicated files. In short, they replicate everything you need to boot and run an operating system—which is why you can’t boot from a simple file-only backup.
So, given all these commonalities, what are the differences between cloning vs. imaging? Which option is better for managed services providers (MSPs)?
Defining cloning and imaging
To begin, let’s start by defining both cloning and imaging.
Cloning is the one-to-one transfer of the entire contents of a hard drive to another hard drive. In other words, it’s the process of creating an exact replica of a drive so you can’t detect a difference between the source drive and the destination drive. With cloning, if something disastrous happens to your source drive, you can revert to the destination drive. The only problem is, you’d miss any changes you made since carrying out the clone—but with that caveat, reverting to the destination drive allows you to pick up where you left off.
You can clone in several ways. If your laptop or desktop allows for two drives, you’re in luck—you can proceed with a direct transfer from one to the other. If, however, you have only one internal drive, you’ll need an external SATA-to-USB adapter, a dock, or an enclosure with which to connect your destination drive to your laptop or desktop. Once the process of cloning a drive is complete, you can disconnect the destination drive and install it internally.
By contrast, imaging is the process of creating a byte-by-byte archive of the contents of a hard drive as a compressed (albeit still very large) file and placing it on another drive. This compressed file acts almost like a big .zip file, but it’s normally saved as an ISO file. Given the compressed nature of image files, it’s possible to store more than one on a single hard drive, move them around your LAN or the Cloud, or even place them on a memory stick.
You can break image files down into two categories—full and differential. Whereas full images include everything on your source drive, differential images contain only the information that has changed since you created your last full image. You can capture these images incrementally so you can account for the latest changes to your data. Given the incomplete nature of differential images, however, they won’t suffice for restoring your drive—you’ll need a full image for that.
Full images are comparable to a destination drive in cloning—but images are not drives. To be functional, you need to open and install them on an existing or new drive using imaging software. Only then can you access your data as normal.
Advantages and disadvantages of imaging and cloning
In the event of a dreaded hard drive corruption or failure, cloning gets you up and running quicker than imaging, though you’ll miss any changes made since you created the clone. All you’d need to do is remove the corrupt or failed drive, insert the cloned drive, and, voila—you’re roughly where you were before disaster struck.
However, the suitability of this type of recovery depends on when you last cloned your drive. If it was recently, you probably haven’t lost much data. However, if you cloned your drive a while back, you can bet you’ve lost any data you created in the interim.
This is the main issue with cloning—it’s a wholly ineffective form of backing up your data. Unlike imaging, you must make a clone manually. Even if you clone your drive periodically—say, every week or two weeks—you can only hold one clone on one drive at any given time, due to the immense amount of space the clones require.
With this limitation in mind, imaging is the better choice for backup purposes. Imaging offers you the option of incrementally backing up your drive using backup software. Assuming you’re regularly backing up your drive, you can rest assured all your data—including the recent additions—is safe. Imaging also allows you to store multiple image files on any sufficiently large hard drive, which provides increased security and flexibility.
Some backup products take an additional step, sometimes referred to as “smart image backup.” Here, you back up everything needed to reboot from scratch, but you don’t back up things that aren’t necessary. For example, you can save a lot of storage space by not backing up temporary internet files or cookies. This more efficient type of image backup allows you to take backups more frequently, resulting in better RTOs and RPOs.
Imaging can also be useful for defragmenting your drive. One reason image files take up less space than clones is imaging omits the free space on your drive, whereas cloning includes it. For this reason, images (unlike clones) aren’t exact replicas of a drive. Similarly, images don’t preserve the physical layout of your original drive. This doesn’t mean imaging alters what you see on your drive—it merely tidies it up by consolidating your data.
The main issue with imaging is you can’t drag image files onto a hard drive to use instantaneously. You need an imaging program—and this introduces a potentially cumbersome step when compared to the process of using a cloned drive.
Which is right for your MSP?
Deciding between imaging and cloning depends wholly on what you want to accomplish.
If you simply want to upgrade from an old or defunct drive to a new one, cloning is likely the way to go. It allows you to replicate the exact contents of your drive onto the new drive quickly and easily. In other words, you won’t need to go through the potentially complicated process of restoring all your data onto a new drive.
If you want to back up your drive, you’ll likely want to turn to imaging—or even better—to smart imaging. This provides you with the option of frequently and incrementally saving the contents of your drive, and thereby allows you to rest assured all your data (rather than most or some) is secure.
For more information on when to clone or image a hard drive read through our related blog articles.