Time machine disk never stops indexing

How do you know that it is indexing, versus something else?

Does your computer do extensive cloud storage and syncing? If so, even if nothing on that drive is being synced, it might get spun up and searched by various cloud processes.

Do you have any anti-virus or third party "cleaner" tools installed? What type of drive is this? Do you have the drive manufacturer tools/utilities installed? [All of these third party tools/utilities of these sorts are not recommended.]

Before discarding the disk, I would check its hardware state with DriveDX. You can also remove it from Time Machine as a backup destination, erase/reformat the entire device, then try again. Make sure you have another reliable backup before doing that.

You can also download and run Etrecheck which is a free diagnostic tool that produces an anonymous report that provides insight into your computer and drive configuration, and software. People will inspect it here if you post it and may find something you can address or fix. Use the Additional Text button below to post the report.

Hey there BobWhitmore,

Try running First Aid on the external drive. Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Open Disk Utility from the Utilities folder of your Applications folder. Choose View > Show All Devices (if available) from the menu bar or toolbar in Disk Utility. The sidebar in Disk Utility should now show each available disk or other storage device, beginning with your startup disk. Beneath each disk you should see any containers and volumes on that disk. Start by selecting the last volume on that disk, then click the First Aid button. You can find more details here:

How to repair a Mac disk with Disk Utility

Take care.

Is the computer a managed device by your employer? I have two MacBook Pros, one an employer device, the other my personal device. Both are set up much the same except the employer one is "managed" which means it can be accessed remotely, configured by employer, etc. Both do Time Machine backups but the employer one often takes notably longer to complete and also has more noticeable disk activity of the sort you mention. Hence my question about managed devices.

I believe indexing shows up as disk activity (especially disk reads) in Activity Monitor, it is reading from the disk, and would be associated with mds processes. However, mds is almost always active in one form or another. Also, I believe you can exclude an external Time Machine backup drive from Spotlight via the Spotlight system settings/preferences. This will not prevent you from restoring from backups.

Disk Utility only reports on the integrity of the file system, not the hardware. You are hearing hardware noises, hence my suggestion to run DriveDX.

Have you tried completely disconnecting from the internet and any local network as well, to see if the noise continues, goes away, changes, etc. Indexing is a local activity and hence would continue if that is what is going on.

I use several mechanical and solid state drives for Time Machine and the mechanical ones are noticeable noisier and have such activity that lasts much longer. You might consider replacing it with an SSD if the noise bothers you.

Hello BobWhitmore,

Welcome to Apple Support Communities!

We want to help ensure the Time Machine backup is complete for you.

See here for why it might take longer than expected:

"If Time Machine takes a long time to back up

Time Machine is designed to work in the background, without interfering with the regular operation of your computer. Time Machine backs up only the changes since your last backup, so after your first backup, future backups should be faster."

This Apple Support page has the full details and more steps to take: If Time Machine takes a long time to back up - Apple Support

If the issue continues, where do you see the messing that it is indexing? What does the specific error message say?

We hope this helps to isolate and resolve the issue causing the drive to continue to index.

Cheers!

FYI, on my employer (managed) computer, the disk activity on the external Time Machine drive has been hugely reduced (on the computer I use) after updating to 13.2.1 MacOS. On both the SSD Time Machine drive and the mechanical Time Machine drive.