Problem with external hard drive and sleep

As this is something that changed when you installed Big Sur, you can use this link to let Apple know in case it is a bug and not by design:

Feedback - macOS - Apple

Apple will not see your problem here as this is a community of end users.

LaCie d2 Thunderbolt 3

I found this on the La Cie site:

https://www.lacie.com/support/kb/compatibility-with-macos-big-sur/

There is mention of updating the LaCie software on some models

Many experienced users don't use sleep, what I an many others use is:

System Preferences - Energy Saver - Turn Display off after....

Set Sleep to never

The reason being is it is much more reliable than sleep and doesn't tend to have the issues sleep does. I've used this setting for close to 20 years and have never had any problems.

izzipol

The best antivirus, cleaning app, and overall maintenance app for Mac OS is Mac OS itself. All you need to do with Mac OS to keep it secure and running well is to keep it up-to-date and do periodic (about 1x per week) restarts. Other than that, leave it alone. Adding third party antivirus, cleaning, security and other types of maintenance apps to Mac OS adds no additional level of security. The only thing these apps do is have the opposite affect users want. They make Mac OS slow, unstable, generate odd behavior (much like you are experiencing) and make Mac OS appear buggy. 

Please locate the developers uninstall instructions for CleanMyMac and follow to the letter. Then restart in Safe Mode per the directions in Use safe mode to isolate issues with your Mac and then restart normally. 

Ensure your Time Machine is formatted correctly which is Mac OS Extended (Journaled) GUID partition. Please do not use other formats.

Same problem. Late 2014 iMac Retina, external Seagate USB used exclusively for TimeMachine on manual backups (which now take an inordinate amount of time). Drive won't spin down, and I can hear it reading or writing constantly. I've reformatted twice — first with HFS+, second time with APFS. The problem persists after multiple repairs with Disk Utility and CleanMyMac X.

Apple, please help.

Thank you. But to clarify, even when I formatted Extended (Journaled), as soon as I select the drive for TimeMachine, the system wraps it in an APFS container. Despite the drive note being solid state. So, it looks like we're not given the choice in Big Sur to use HFS+ on a hard disk drive with TimeMachine.

Indeed, I noticed the same thing and glad to learn I am not alone. I'll probably end up ditching Time Machine. Between APFS hassles, constant and nosily indexing (I first thought the drive was actually broken) as well as the the inability to now clone a TM volume to another drive Apple succeeded in putting the pain back in into making backups.