Continuing Time Machine backups with new internal HDD

I have a mid-2010 Macbook Pro. It came with a 500G internal. For a couple of years, I've been using a 1TB external for Time Machine backups. As of a couple of weeks ago, I'd reached only about half of the capacity of that external HDD.

Last week I swapped my 500G internal for a new 1TB internal. Before I did that, I cloned my internal with SuperDuper. Then I switched HDDs and migrated everything over. No issues. So now I have a new 1TB internal with about 600G free.

Tonight I hooked up my regular Time Machine to the MBP. It didn't automatically start backing up, like it used to. I figured it was "used" to the old internal, so I manually selected my new internal and it started to backup..... the entire drive. Not an incremental backup (probably about 30 gigs). I checked the contents of the Time Machine external, and all the old TM backups are there, perfect and accessible. Why won't it scan my new internal and back up only the changed or new files?

You're almost right about it being used to the old drive but that is a story for another day. Give this a quick read it should do the trick.

Thanks, Slydude. Unfortunately I'm not sure this solution works for me. My issue is using the same external drive I've used for Time Machine (with my original internal 500G HDD), and continue incremental backups with my new internal 1TB. The external just sees my new internal as a completely new computer and will not pick up where it left off, Time Machine backup-wise.

Sorry, I wasn't paying close enough attention when I created that link. Have a look at this article instead. The steps for how to solve this issue depend in part upon whether the Time Machine backup ws data only or also contained system files.

When you said Time Machine was "used to" the old drive you were essentially right. Time Machine uses a drive ID number to differentiate various drives that reduces the prospect of overwriting data on another drive that happens to have the same name as your Time Machine drive.