CafeTran

I'm using OS X 10.11.2 and I have two external drives (USB) that I've erased (HFS+ Journaled). I upgraded from Yosemite. When I try to create a back up, my MacBook Pro Retina is stuck in the Calculating stage. On both drives. Erased both drive twice.

Rebooted. Solved.

Only yesterday, I created a new Time Machine back-up on a reformatted HFS+ disk, so it isn't El Capi.

Unless something went wrong when installing it. In your case, it's highly unlikely that two drives failed. And I did exclude the disk from Spotlight indexing (a lengthy process).

H.

No, But they are empty. And I've used this procedure until El Capitan many times (erasing the external disk to create a compact back up).

Did you exclude the Time Machine drives from Spotlight indexing?

H.