Time machine HD keeps pounding and spinning all the time

If your Time Machine HD is continuously pounding and spinning, it could be due to several reasons:

1. Backup in Progress: Time Machine automatically backs up your data at regular intervals. During a backup, the hard drive will spin and work intensively, which might cause the noise you're hearing. This is normal behavior.
2. Large Backup: If you have a large amount of data to back up, it can take a while for Time Machine to complete the process. The hard drive will remain active until the backup is finished.
3. Backup Error or Issue: Occasionally, Time Machine backups can encounter errors or get stuck. In such cases, the hard drive might continue to work as it tries to complete the backup. You can check the Time Machine settings or the Time Machine preferences pane for any error messages or issues.
4. External Factors: Sometimes, external factors like file indexing or other system processes can cause the hard drive to work continuously. This can happen if your computer is indexing files, performing system updates, or running maintenance tasks in the background.

To address this issue:

1. Monitor Backup Progress: Check the Time Machine preferences to see if a backup is in progress. If it is, let it complete.
2. Check for Errors: If there are no ongoing backups but the drive is still active, check for any Time Machine errors or issues in the Time Machine preferences.
3. Restart or Reset: If you suspect a stuck backup or other system issue, try restarting your Mac. This can often resolve background processes causing high hard drive activity.
4. Monitor Activity: You can use the Activity Monitor (found in the Utilities folder within the Applications folder) to identify which processes are consuming system resources, including the hard drive.
5. Seek Professional Help: If the issue persists and you're concerned about hardware problems with the hard drive, consider seeking assistance from an Apple-certified technician or a professional data recovery service.

In most cases, Time Machine's activity should subside once backups are complete, and the hard drive should return to a more typical, idle state.

It could be Spotlight Indexing the external 10T Seagate drive.

see > Rebuild the Spotlight index on your Mac - Apple Support

Go to > Apple > System Preferences > Spotlight and check to see if the 10T Seagate is listed.

If it is listed, highlight it and click the - to remove it from Spotlight Indexing.

You do not want to add it to the list.

I was just checking to see if it somehow was in the list of items being Indexed.

The other two things that I can think of are,

1) A process using the external drive has failed or is unresponsive.

To check for a failed process, go to Apple > Force Quit and force quit any process listed in red.

see > How to force an app to quit on your Mac - Apple Support

Another way to look for a failed process, is using your Activity Monitor.

see > Activity Monitor User Guide for Mac - Apple Support

2) The external drive is failing and needs to be replaced.

To check run Disk Utility > Repair on the Seagate external drive.

see > Repair a storage device in Disk Utility on Mac - Apple Support

Years ago there were some drives that used to emit a ticking sound fairly often.

When we looked into it, we discovered the drives were NOT storing files at the time, they were doing an internal thermal re-calibrate cycle. The ticking was caused by the extremes series of seeks and reads required for re-calibration.

It turned out to be not an issue, unless you demanded silence.