Dropbox is not a backup service

At Least By Default . . .


The Story

One of my faculty members came to me recently because s/he was getting “low free space” warnings on the hard drive of their ThinkPad. S/he couldn’t understand how their hard drive was so full. “I keep most of my stuff on my Mac at home. I just use this for email.”

So I took a look at the machine with SpaceSniffer (a great tool, but that’s another post for another time). The Dropbox folder was a massive space eater. When I pointed it out, s/he said “Yeah I use Dropbox to backup my Mac. Sometime I need a file from the Mac, so I installed it on my ThinkPad.”

Time to educate my users and clear up a common misconception.

The Explanation

Dropbox was designed as a data syncing tool for people with multiple computers and devices. Files on one device that are monitored by Dropbox are copied to all devices on which Dropbox is installed.

dropbox setup dropbox syncs files between multiple devices

If you change a file that Dropbox monitors one one device, that change is propagated to all your other devices that have your Dropbox installed. That means there are copies on each device.

  1. You put a piece of data on one of your computers in the Dropbox folder (ex. Song1.mp3).
  2. That piece of data is copied to your Dropbox account on the Dropbox’s servers (“in the cloud”) and then immediately sent to every other device on which you have installed your Dropbox.
  3. The problem is that if a file one one device is altered, then the alteration is propagated to all the devices. Dropbox neither knows nor cares whether the alteration is intentional or accidental. It just does the job of syncing (see Note 2 at the bottom of the post).

Let’s look at some potential scenarios that might be problematic:

  • You delete file2 from your Mac. Now file2 gets deleted from your ThinkPad, your Phone, and your Dropbox account online.
  • On your Phone, file3 gets corrupted somehow. That corruption is copied over to ThinkPad, Mac, and Dropbox online account.
  • The cryptolocker virus locks up the data on your phone by encrypting your ThinkPad. That’s a change, so Dropbox copies the now encrypted files to the other devices.

In the case of my particular faculty member, they didn’t understand that Dropbox’s functionality. I believe they thought that they were accessing the mac files in the cloud instead of understanding that those files were being copied down to the ThinkPad.

Cloud backup

Cloud backup would put copies of the files on a given device into the cloud. It would not copy them all down to all the devices.

cloud backup for multiple devices


Notice the arrows in the images are one-way. The backup service is not copying data back down. That’s the difference between sync and backup.

Dropbox as a backup tool

Although Dropbox (or Google Drive, or Microsoft OneDrive, or Apple iCloud, etc) are mostly cloud storage and cloud syncing, they can be used as cloud backup. There are just extra steps you have to take. Those steps will vary from service to service. How To Geek  released an article discussing how to do it for many of the tools.

Note: the article doesn’t cover iCloud specifically, but you should be able to extrapolate. If not. . .

Note 2: Dropbox by itself is not a sufficient tool to be a primary backup system in my professional opinion. It is great as a secondary level because it does keep a limited history of file versions.

If you are only going to have one tool for backup, use one that is designed to be a backup tool, like SpiderOak, Carbonite, or dedicated external media.

The Office of the Dean of the College at Wake Forest University purchases SpiderOak backup solution for full-time, permanent faculty. Please contact the ODoC in order to determine if you have questions regarding your eligibility.

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