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Is it better to use incremental or differential backups?

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Hi Leo. In January, I made a full image backup of my computer using Macrium Standard and scheduled a nightly differential backup. I chose differential over incremental as it’s easier to restore using the full image plus the most recent differential rather than restoring the full image and every subsequent incremental. To make sure I retain enough disk space for backups on my external drive,  I delete all the differentials every 10 days except for the last two. Based on this scenario: 1) Would there be any advantage to making monthly full image backups as you suggest rather than just sticking with my January image? 2) Would there be any advantage in using incrementals instead of differentials? 3) It’s now June and I am a happy camper! Is there any reason I shouldn’t be?

Well, first let me start with the last question first. Nope, you’re in great shape!

I’m thrilled that you’re backing up. You’ve clearly put some thought into this, and I don’t have any serious issues with the approach that you’re taking. If you’re comfortable with what you’re doing, I probably wouldn’t have you change anything.

But if there were something that I’d recommend that you change, it’d be taking a new full backup probably once a month or so. Why? That gets a little harder for me to explain.

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Taking monthly full backup

There’s really no technical reason for a monthly full backup. With a differential backup, it doesn’t matter if you created the backup a month ago, six months ago, or a year ago. As long as it’s applied to a consistent full backup that was taken at some point in time in the past, the amount of time shouldn’t matter.

On the other hand, I get nervous very easily. When it comes to backups, I like the concept of having something more recent just in case.

Just because I know that:

  • Software occasionally goes a little wrong.
  • Life conspires against us.
  • All my years in the industry makes me a little superstitious.
  • Whatever other reason you want to throw in here.

My recommendation is not based on any rational reason. I’ve just had way too many experiences where something I didn’t expect to happen actually happened.

Is it a huge deal? Absolutely not.

Like I said when I started, I’m comfortable with what you’re doing, but if it were me, I would probably add an occasional full backup into the mix just to reset your clock on the backups that you have.

Make a backup reminderIncremental versus differential backups

Now, to answer your second question: is there any advantage in using incremental backups over differential backups? Yes and no.

Typically because incremental backups are smaller it’s what most people use to keep the amount of space taken up by backups under control. Obviously, you’re doing a fairly reasonable job of managing your disk space by only keeping a few differential backups. That’s a good approach.

On the other hand, I do an incremental backup every night, and I reset the clock with a full backup once a month. That way, I will always be able to recover a file as it was on any day in the last month.

For example, let’s say that I have a file. I make a change to the file and save it, but in the course of my work, I accidentally delete the file. Unfortunately, I don’t realize that I deleted it until a week and a half later when I can’t find the file.

Because I remembered the date when I changed the file, I can find that file on my incremental backups taken the day before or after the file was changed.

When you discard backups so that you’re only keeping the last couple, you don’t have that option. You have a backup of your machine as of the last couple of days: the full backup from January, and the differentials that reflect the changes as of a couple of days ago and last night. But you’ve lost all of that daily granularity.

And yes, you can use this process with differentials as well, but a differential will include all of the changes since January in each copy of the differential every time you take a differential. The incremental will only include the changes made since the last backup of any kind.

Basically, the issue comes down to space management. I like granularity – the idea that I can go back to any time within the last month and pick something up that I may have overwritten or lost.

Nonetheless, I’m just really pleased that you’ve put a lot of thought into this. If you’re a happy camper with this scenario, then I’m a happy camper, too.

11 comments on “Is it better to use incremental or differential backups?”

  1. I currently use Acronis True Image Home 2014. A cycle of full backup of both hard drives in the laptop, Drive 0 is Windows 8.1 Pro
    1tb 2.5 5400 SSHD (GPT) and Drive 1 is Windows 7 SP1 Professional 2tb HDD (MBR), I do a full backup with 4 differentials for 4 cycles.
    I use TIH2014’s on complete script to then copy the newly created .tib file to a separate external 4tb HDD (to backup the backup).
    That covers media failure for the backup media. I keep a spare hard drive of both sizes and a couple 4TB externals. I can do bare metal
    recovery and be back up in a couple of hours. I used to use incrementals but having corrupted incremental files loosing the whole chain
    was unacceptable. I also have a spot full backup of the windows 8 system as delivered to cope with no install media provided.
    The manufacturer does offer to sell a set of DVDs for restoring to OOBE, but was unclear as to if they depended on a on-disk
    recovery partitions which would not exist in a media failure scenario. My setup is probably overkill, but it does what I need it to do.

    Reply
  2. One method of using incremental backups successfully over the long term is to create two separate backup folders. Create two separate backup folders and fill them on alternating days. For example, folder1 includes a full backup on a Monday, then continues, incrementally on Wednesday, Friday and Sunday. Then, Folder2 starts with a full backup on Tuesday, then is filled incrementally on Thursday and Saturday. This can go on for a year. Then… when the backup drive is getting reasonably full, all you have to do is to delete one stream – folder1 or 2, then restart that folder with a new full back up and incrementals. This way, you’ll always be able to go back very far, in case you deleted a file, messed something up, or had a virus begin quite a ways back! Every year or so, you can delete one or the other, you have a redundancy alternating by one day separation and yet still are keeping your file space usage down.

    Reply
  3. I have been doing backups since 1984. Backup applications have let me down several times. The worst was a trial restore after a backup. The corrupted backup destroyed the original files. I know several horror stories about recovering a file that was corrupted or deleted many months ago.

    I have just switched from Acronis to Macrium. I use their grandfather plan (Full monthly, Differential weekly, Incremental daily). I also retain an annual clone of each hard drive (C D E F this year and last year).

    Do Macrium Incremental backups really work the way you implied? I hope not. A “DOS copy” command would do a better job. Differential Monday. Incremental Tuesday, Wednesday, etc. I change a file on Tuesday and again on Wednesday. If the Tuesday incremental is corrupt, the Wednesday version should be available. I should only lose files that were changed Tuesday, but not since then?

    Reply
  4. One small comment.

    Hard drives have become so reasonable I’m a big fan of the 3 drive system (only because of a limitation of Acronis True Image with laptops). An annual clone, monthly full backups with weekly differential backups on monthly alternating hard drives with offsite storage of the clone and semi monthly backups. The limitation of Acronis True Image is the requirement to remove the hard drive from the laptop in order to clone it. With many new laptops this requires extensive dis-assembly of the laptop, removing the back, top and keyboard of the laptop to access the hard disk, which in some cases will void the warranty. The average user simply isn’t equipped or inclined to go through this much of a hassle. This limitation in part affected the purchase of my current laptop – one where the HD is located under an easily removed back panel.

    Reply
    • I’ve never heard of anything like that, but it’s a feature not a shortcoming. It’s a great idea that they don’t allow backups to an internal drive. The chances are too great of an electric surge or malware which can damage all of the internal drives. Those things can also damage external drives, but the risk is smaller.

      Reply
  5. I had run a full backup. A week later I thought I would try a differential thinking it would be short and quick. After letting it run for an hour or so and seeing that it was only 5% complete it sure seemed to me that something was wrong. Shouldn’t incrementals and differentials run fairly quick?

    Reply
  6. Are you saying that with an incremental backup you can use any one of the increments which contains the file you are seeking?
    I thought that only the backup/restore program (Macrium, Acronis, etc) would be able to process the data.

    Reply

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