17GB difference in backup size

[The VCR King]

I have all the files (OS and entire HDD) set to backup. However, the files on my main hard drive take 445GB of space, but my backup is 462GB in size. Earlier my main HDD's files and backup file were the same size, but now they are different sizes. I haven't modified any settings or changed what gets backed up, so why is my backup file larger than the files being backed up?

 

[johnb35]

Have you tried comparing them? Maybe you saved something to that drive and didn't remember? Go folder by folder on each drive and compare.

 

[beers]

Probably hibernation file and page file. They're only used on one device. Since the size is around double your RAM quantity than it's probably the first thing to look at.

Why don't you compress or archive any of your backups?

 

[Geoff]

Just an FYI too, if you are simply copying files between the two, there is no point in copying the OS and applications as you wouldn't be able to copy them back in the event of an OS corruption. If they were images that would be one thing.

To your question, it's either temporary files created on the backup drive by your backup utility, or the page file and hibernation data that were copied over initially, are no longer present, or at least as large on the main disk.