Backing Up The Backup

I don't use SuperDuper but assume that it has similar features to other standard backup applications that allow you to back up a network drive like a Time Capsule or NAS. Simply set up SuperDuper to back up the Time Capsule drive......named "Data" unless you have changed the name......to another destination drive. That drive could be connected to the USB port on the Time Capsule or to your Mac.

Here is what something like that would look like on CCC if I wanted to back up everything on my Time Capsule disk to another hard drive.

Backups is the name of my Time Capsule disk. Backups 2 is the name of a USB drive connected to the Time Capsule, but it could be connected to my Mac if I wanted to set it up that way. CCC will backup daily at 9 PM copying only the files that have changed on Backups since the previous backup that occurred the previous day.

Now, if SuperDuper cannot back up a network drive to another destination, you would have to use CCC or another application that can do this. I haven't checked recently, but ChronoSync should allow you to do the same thing.

Like LaPastenague, I am not a fan of backing up a backup though. A better plan would be to simply have Time Machine back up to another drive in addition to the Time Capsule. But, it's your call.

How can I use SuperDuper as a backup program for Time Machine?

When I tried to set this up, with SuperDuper I couldn't find the Time Capsule as a source

That is or was a weakness in SuperDuper and why I recommend Carbon Copy Cloner as the better program.

How old is your SuperDuper version.. because I did hear it had been updated to accept network sources.

But your situation I think just using Time Machine is a better idea. It can easily backup to both Time Capsule and EHD from local disk source. That should ensure you are never without a backup. And the local backup is far superior for reliability and speed into the bargain.

You can simply add it to the existing backup.. use Add disk in Tme Machine Preferences. You will be asked if you wish to continue using both.. say yes.. easy.

My only remaining question is which drive comes up when I open Time Machine, the original or the new second backup drive?

I have Finder Preferences set up to display the network path at the bottom of each Finder window, so it is easy to see whether the Time Machine backups displayed are on the Time Capsule or on another hard drive. I can't take a screenshot of the actual Time Machine window because that feature is not available in Time Machine, but the Time Machine window looks similar to the example below.

Backing up the backup is never a great idea.

The reason is simple.. if the first backup is corrupt the second is as well.

You have explained the setup very well. Took several readings to pick up all the details.

Point 3 I have a question.

3 If my Time Machine goes down.............I've lost all the saved past files, etc.

I presume you are mixing up Time Machine.. backup software on the Mac and Time Capsule.. a hardware router with internal hard drive. And no if you make an archive of the TC now you have a backup record of your past files.. no need to have another backup.

So from there to the question.

4 Do I backup my Time Machine, and if so, how?

My reply is no.. if you mean continuous backup. For the very good reason that it is difficult to do.. Time Capsule has no built in incremental backup.. just a simple archive.. i.e. copy all files on the internal disk to USB drive. For a full 2TB drive this can take up to 24hours. And without incremental built in that means it never stops. Nor does the TC accept backups while archiving. So that is out. If you are worried the TC is going to die.. especially if purchased at the same time or earlier than 2013 iMac then yes.. it is definitely worth it because TC do die suddenly. And 5years is about the lifespan you can trust and even 3years is not unexpected.

The standard hard disk in the Mac is no better.

You could plug a USB into the TC and archive with your cloning software.. like Carbon Copy Cloner.. from the computer. The issue here is Time Machine sparse bundles probably cannot be copied as incremental and so you will end up copying the whole thing anyway. Not sure on that one.. I have not done it for reasons stated above.

Anyway it is going to be super slow because files must be copied via the computer.. and USB on the TC is SLOW. Like.. S--L--O--W. Every file is copied TC to computer.. Computer to TC.. TC to S--L--O--W USB.

5 Or do I create two Time Machine backups? What is the best way? Alternate days on two drives, or is there a way to create two Time Machine backups simultaneously on two drives?

Yes.. you can do this. I don't think it is needed if you moved all the current Sierra user files to the EHD for Catalina.

Time Machine supports multiple drives.. it will simply rotate them in order.

Can you clarify which OS you are talking about because this is getting complicated.

Sierra on the internal slow disk.. Catalina on an SSD I presume external drive. You don't need to keep backing up Sierra.. since it is not being used generally. You can leave Time Machine running on Sierra for if/when you boot from it. Backup to USB plugged into the TC could save you if the TC breaks down.

A simple archive of the TC onto the USB drive will work to preserve TM backup in case of total failure.. then wipe the TC drive and start afresh with Time Machine from Catalina. Nor do you need two Time Machine backups..

You could use a larger USB plugged into the TC as a second target.. partition it in two parts. One for archive and one for current backups from your Sierra and Catalina..

Note.. Time Machine is not especially reliable in Catalina.

Your practice of cloning is good.. so keep that up.

What cloner are you running? CCC can certainly maintain a store of incremental files.. not as neat as Time Machine but good enough for most people.

Reading back through this and trying to fix it is making it even more complicated.

I need guidance as to what you are really trying to achieve.

I seem to have recommended a stack of USB drives.. and have already said this is slow.. and yes it is slow.. but Time Machine incremental are small and even with slow backup it still will be fast enough.

There are several complexities here.. and backing up to local drive is still better arrangement.. much faster.. much more reliable.

As a btw.. I used Time Machine on a large external USB plugged into the computer.. this is partitioned to also take the CCC bootable clone. My experience with Time Machine reliability became such that I leave it turned off now.. so occasionally run it.. CCC (Carbon Copy Cloner) is now my main backup.

Not really recommending that you do this, but if you connect a USB drive to the USB port on a Time Capsule,, you can use the Archive function in AirPort Utility to back up everything on the Time Capsule hard drive to the USB drive.

The downside here, is that the Archive backs up everything on the Time Capsule hard drive every time you run it. So, the hard drive connected to the USB port on the Time Capsule will fill up very quickly and you'll have to erase it and start over again frequently.

Things would be much simpler if you used another application like Carbon Copy Cloner to back up all the data on the Time Capsule hard drive to a USB drive. After the first initial copy, CCC will only back up any changes that have occurred on the Time Capsule hard drive since the last backup.

Another option.......if you don't need all the old history of backups on the Time Capsule copied over to another drive and you can start fresh with Time Machine.......would be to back up using Time Machine to both the Time Capsule and another hard drive. Then, Time Machine will automatically alternate backups between the Time Capsule and the other hard drive.

You will still have the history of backups on the Time Capsule and start building a new history of backups on the other hard drive.

The big question is whether you really do need to back up a Time Machine file with data from weeks, months and even years going back in time. Few of us ever need this type of "feature"......but some users do. All that most of us really need is a current backup of the Mac in case the Mac's hard drive fails. Then, after the Mac has been repaired, you can copy the current backup back over to the Mac so it will look just like the Mac did before it failed.

did the new EHD backup go into the past, or only begins with today's backup?

A "new" backup will go as far back in time as the date on which you originally set it up. So, if you set up a "new" backup yesterday, the history will go back one day.

More info on displaying the network Path in Finder windows is here:

https://www.lifewire.com/use-macs-hidden-finder-path-bar-2260868