Backing up to an internal drive isn’t all that different from backing up to an external one.
Each has pros and cons, as do other backup options you might consider.
I’ll walk you through the most common.
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Backing up to the same drive
Before I discuss your question, let’s look at the scenario that makes most knowledgeable techies cringe: backing up to the same drive.
For example, let’s say you back up your documents folder to another folder elsewhere on the same drive — maybe the contents of “C:\Users\You\Documents” is backed up to “C:\Backups”.
This protects you from:
- Accidentally erasing, modifying, corrupting, or otherwise damaging your documents. You can simply restore them from the backup copy.
This does not protect you from:
- Hardware failure. If your single hard-disk drive dies, you lose everything on it, including your backups.
- System failure. When using this approach, it’s difficult (if not impossible) to back up your entire system. If your Windows installation fails for any reason, this is not an approach that will allow you to revert to a backup copy.
- Malware. If viruses or other forms of malware corrupt your system, your files, or even entire drives, both the original and backup copy on the same drive would be at risk.
- Theft, fire, tornadoes, earthquakes, and the like.
Backing up to an external drive
This is a recommended approach. It’s what I often tell people: “Get an external drive and backup software and make sure your system is getting backed up regularly.”
This protects you from:
- Accidentally erasing, modifying, corrupting, or otherwise damaging your documents. You simply restore them from the backup copy.
- Hardware failure. If your system disk dies, you replace it and restore from the backup. If the backup drive dies, you replace it and resume backing up.
- Most system failures. Should your installation fail for any reason, you can revert to a backup rather than reinstalling Windows from scratch.
- Most malware. Recovering involves restoring a full system backup taken prior to infection.
This doesn’t protect you from:
- Malware that infects connected drives.
- Theft or disasters that would take out all of the computer-related equipment in your home.
That’s a long list of pros without too many cons.
Backing up to an internal drive
This is backing up to a second, physically distinct drive inside your machine. Backing up to a different partition on the same drive is exactly the same as backing up to the same drive, as discussed above.
The only real difference between backing up to a second internal drive versus an external drive is the connection to and location of the drive. Most of the pros and cons of the external-drive scenario above still apply.
There some subtle differences.
- The internal drive will be faster. Thus it may be more likely to be used for day-to-day things, as well as backups. How that usage impacts backups will vary, but typically, the impact is reduced disk space for backups. In addition, some alternate means of backing up that data needs to be considered.
- An external drive is more electrically isolated from system. This means that certain types of electrical failures that might damage an internal drive might not damage an external drive.
- An external drive is quickly and easily replaced, making it easy to upgrade or swap out as needed. Unfortunately, that makes the drive easier to steal.
Short summary: Backing up to a second internal drive is a surprisingly reasonable choice, and shares most of the same characteristics as backing up to an external drive. Some of the differences boil down to convenience.
Backing up to offline media
Offline media — typically CDs and DVDs, but this might also include flash media — used to be a common form of backup.
The biggest advantage to these destinations is that once written, they cannot be modified, and they’re disconnected from the computer once the backup is complete, so they’re not impacted by any subsequent machine failures.
The drawback is, they’re relatively small compared to the amount of data we want to back up. Backing up anything large — particularly a complete system — takes so many CDs or DVDs, for example, that it becomes unwieldy and impractical.
Online backups protect what’s backed up from almost everything practically imaginable, shy of account theft.
They still have one fatal flaw, in my opinion.
The amount of data needed to be backed up for a full system backup is so huge as to make online backups impractical. Depending on the speed of your internet connection, a complete system backup would take days, if not weeks, to upload.
The compromise, then, is that online backups are used to backup important data, but not used to back up your system.
Backing up in any form is better than not backing up at all. Exactly how you should back up depends on your abilities and your needs.
One of the reasons folks such as myself often recommend an external drive and backup software is because it’s easy to set up and it gets you the most bang for your buck: significant protection from the most common disasters (hard drive failures and most malware).
If it’s easy, more people are likely to do it.
Backing up to a second internal drive could be a worthwhile approach, as long as you understand what is and is not being protected as a result.