Backing up multiple drives to one external HD using Time Machine

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Backing up multiple drives to one external HD using Time Machine

I have an external 4 TB HD and wanted to back up: 2 external 1TB HDs and the internal HD for my iMac. I did this the other day and confirmed that the files were for my 2 external HDs and one internal HD. Then, today, I went to back up only my internal HD again and noticed that the files for my two externals had been deleted. They were deleted despite the fact that the 4 TB backup drive should have had plenty of space (ie, Time Machine shouldn't have been deleting files to make room). Can I back up multiple drives like I'm trying to do onto one, larger HD? Now that I look at it, this should be in the Big Sur forum, but I'm unclear on how to change it.

Posted on May 22, 2021 8:28 PM

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Answer 1

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TheKid43 Author

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May 24, 2021 6:20 PM in response to BDAqua

I felt like trying to back the two externals as well as the iMac was complicating things. So I looked up how to partition the disk and set up half as a dedicated TM and half as just storage. This seems to be working. Now, after having disconnected and then reconnected the external TM disk, it backs up incrementally which is what I wanted it to do. In the past, it was generating a back up from the ground up. Now, it's just a question of throwing the two externals onto the free storage area and I think I'll be fine. Thanks for the suggestions.

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Answer 2

TheKid43 Author

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May 23, 2021 8:10 AM in response to BDAqua

The externals weren’t connected when I noticed the missing backups. The only other information I can think of that’s possibly relevant is that I was using two different configurations for two backup disks on TM. I have one backup disk that’s wireless and wanted to keep plenty of space on that one, so it’s set to only back up the 1 TB iMac HD. Then, I set the larger external (4TB) to back up not only the iMac HD, but also the two smaller externals. If there doesn’t seem to be an issue with this configuration, I’ll just try everything from scratch which isn’t a big deal.

Thanks so much.

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