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.
Incremental 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.