Skip to content

Why does Time Machine need a Spotlight index of the backup?

  • by
Spread the love

This subject has been touched on here, but in my opinion not answered at all.

I’m trying to understand why Time Machine needs Spotlight. It’s widely stated that it does, but never explained why. I can’t think of a reason. What would be the effect of never letting Spotlight complete it’s indexing of the Time Machine backup ?

My context: I’m backing up a new M1 Macbook Pro, and a new M2 Macbook Air, to separate USB SSD drives. This is a temporary measure until I get a new WiFi backup device. I’m doing it manually about every one or two days. So I plug in the USB drive and when the backup finishes the disk keeps flashing away and various “md” processes are very busy – mdsync, mdworker_shared, mds. Usually I just unmount and pull out the USB drive. Nothing seems to go wrong, and I can still remount it and “Enter Time Machine” and recover some file I need. (I’ll swap to a new WiFi backup device some time soon, I don’t want to trust my many-years-old Time Capsule any longer). So I don’t have any idea why Time Machine “needs” Spotlight. There must be many scenarios where the user backs up and then disconnects the drive, as above. In fact it would be forced on you in some scenarios, eg. a shared backup drive across several Macs. For example, I might decide to use a single SSD USB drive for both the Macs mentioned above. It wouldn’t be feasible to sit and wait for Spotlight to finish an interminable indexing operation, when I need to pull out the drive and backup the other Mac.

I’d like to understand this to be sure I’m not exposed to any risk here. Many thanks.

(Hope this question satisfies the moderators. I’ve read all the suggested related items, and many others on other sites, and I’ve not found the answer).

Leave a Reply

Your email address will not be published. Required fields are marked *