Backing up 2 drives to one Time Machine?

[Darmok N Jalad]

I just added a USB 3.1 SSD drive to my iMac for my less-used files (like videos and older RAW photos) and download archives. I also have a USB 3.0 spinning drive that I already use as my Time Machine. My questions are, can I backup both my iMac's internal drive and my external SSD drive to the same Time Machine drive, and if so, how does that look on the Time Machine drive itself? If I need to restore my iMac, how would that affect the SSD? Could I restore my iMac without needing to restore the SSD, or would that mess up the whole process?

 

[techwarrior]

TM automatically excludes external drives and can't remove them from the exclude list.

Your TM target drive is able to be used like any regular external drive, so you can manually copy files from the external SSD to the TM drive. This can either be on the same partition as backups, or if you create a 2nd partition on the TM drive, the folder could be on the 2nd partition. A single partition would generally be more efficient, but partitioning the TM drive in effect creates a quota for each category as TM purges oldest files when it runs low on space.

The Mac App Store has several Folder Sync apps, a few free. I haven't used any of these, but it looks like these could be used to keep folders on the SSD in sync with folders on the TM disk, including bi-directional sync.

MacOS also has a command line tool, rsync, which can sync Source > Destination (not bidirectional). This could be put in a bash script and run nightly using crontab if you are handy with scripting and Terminal. The rsync command has a number of options for filtering, archiving, compressing, etc.

 

[Darmok N Jalad]

TM automatically excludes external drives and can't remove them from the exclude list.

Your TM target drive is able to be used like any regular external drive, so you can manually copy files from the external SSD to the TM drive. This can either be on the same partition as backups, or if you create a 2nd partition on the TM drive, the folder could be on the 2nd partition. A single partition would generally be more efficient, but partitioning the TM drive in effect creates a quota for each category as TM purges oldest files when it runs low on space.

The Mac App Store has several Folder Sync apps, a few free. I haven't used any of these, but it looks like these could be used to keep folders on the SSD in sync with folders on the TM disk, including bi-directional sync.

MacOS also has a command line tool, rsync, which can sync Source > Destination (not bidirectional). This could be put in a bash script and run nightly using crontab if you are handy with scripting and Terminal. The rsync command has a number of options for filtering, archiving, compressing, etc.

Thanks. Yes, I currently have my TM HDD partitioned in 2 equal volumes, one for TM backup, the other as a traditional Volume. I used them like this before adding the SSD and didn’t know if I should change my strategy. A sync system would be nice, as it’s hard to keep track of changes on a drive that’s already mostly an archive. Occasionally I go into this archive and clean it up, as it’s 15+ years of files.

 

[ItWasNotMe]

TM automatically excludes external drives and can't remove them from the exclude list....

.

Not true, you can backup any drive onto a TM drive, internal or external.

• 'Open Time Machine Preferences'
• Select 'Options'
• Highlight the drive you want to backup
• Select 'Minus' button to remove the drive from the list of exclusions
• Select 'Save'

Time machine will then backup the external drive

Once Time Machine has backed them up they appear alongside the internal drive, with same structure as the source.

 

[Darmok N Jalad]

Not true, you can backup any drive onto a TM drive, internal or external.

• 'Open Time Machine Preferences'
• Select 'Options'
• Highlight the drive you want to backup
• Select 'Minus' button to remove the drive from the list of exclusions
• Select 'Save'

Time machine will then backup the external drive

Once Time Machine has backed them up they appear alongside the internal drive, with same structure as the source.

So how would restoring work in this situation if the external drive failed?

 

[ItWasNotMe]

So how would restoring work in this situation if the external drive failed?

Exactly same mechanism as if you had to restore your internal drive from Time Machine.

• Get a new drive to replace the failed one
• Enter Time Machine
• Within that navigate to the latest backup of the appropriate drive
• Choose 'Restore to"... the new disk

 

[techwarrior]

Not true, you can backup any drive onto a TM drive, internal or external.

• 'Open Time Machine Preferences'
• Select 'Options'
• Highlight the drive you want to backup
• Select 'Minus' button to remove the drive from the list of exclusions
• Select 'Save'

Time machine will then backup the external drive

Once Time Machine has backed them up they appear alongside the internal drive, with same structure as the source.

My bad, I have several drives attached to my Mac and most are greyed out and cannot be removed from he exclude list. My TM drive (USB) is partitioned with DATA and Time Machine and cannot be removed from the exclude list. TM makes sense, but the DATA partition is FAT formatted, so it cannot be removed from the exclude list, as well as flash drives (FAT).

The key seems to be macOS format external drives can be included in backups, but other formats cannot.

 

[Longkeg]

Exactly same mechanism as if you had to restore your internal drive from Time Machine.

• Get a new drive to replace the failed one
• Enter Time Machine
• Within that navigate to the latest backup of the appropriate drive
• Choose 'Restore to"... the new disk

It might not be necessary but to play it safe I always give my replacement drive the same name as the drive that failed. That way TM thinks it's restoring to the original drive.

 

[ItWasNotMe]

...

The key seems to be macOS format external drives can be included in backups, but other formats cannot.

Agreed, bit too loose with my phrasing and use of 'any'. As a source, HFS+ or APFS should be fine.

 

[Darmok N Jalad]

Thanks for all the input. I setup my Time Machine drive to backup both the internal and external drives and it went just fine. I see now that it divides the 2 drives inside of Time Machine.

 

[mund]

Should the Time Machine drive be portioned to accommodate the drives being backed up?
(Meaning if you have (3) drives to back up, create (3) partitions to better accommodate)

 

[Darmok N Jalad]

Should the Time Machine drive be portioned to accommodate the drives being backed up?
(Meaning if you have (3) drives to back up, create (3) partitions to better accommodate)

It shouldn’t be necessary, in fact, it might hamper the space you have reserved for Time Machine depending on your use. Time Machine will sort each drive out on its own. Each drive gets backed up to a folder on the TM drive.

 

[mund]

It shouldn’t be necessary, in fact, it might hamper the space you have reserved for Time Machine depending on your use. Time Machine will sort each drive out on its own. Each drive gets backed up to a folder on the TM drive.

Thank You.. I guess I am overthinking this a bit.
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Thanks for all the input. I setup my Time Machine drive to backup both the internal and external drives and it went just fine. I see now that it divides the 2 drives inside of Time Machine.

Awesome to hear... looking forward to the same success.