This article will not cover ALL possible or available backup applications for the Mac family. But it will cover two approaches to backups: clones and synchronized.
Cloners do just that, they make a clone, or a complete copy, of the object drive onto the target drive. Two of the more popular are Carbon Copy Cloner by Bombich (https://bombich.com) and SuperDuper! by Shirt Pocket (https://www.shirt-pocket.com). Each of those will make a full or partial clone backup and each offers the opportunity to preserve older copies of files in the backup. Both can be scheduled to make the backups automatically.
So, how does a clone work and why would you want one? A clone can be a complete copy of the source drive, including the operating system. “Complete” means that the cloned backup should or could be bootable. Being able to boot from the backup is a good thing for businesses that depend on the Mac for income and who cannot tolerate any lost time. If the internal drive in the Mac fails, the machine can be booted and run from the backup just as if nothing had happened. While waiting for a replacement drive to arrive to replace the failed hardware, the user can just keep going. When the new drive arrives and is installed, the clone software can be used to put back on the new internal drive what is on the external. Little to no interruption in operation!
There are some complications with cloning for more modern versions of macOS and Mx systems, as discussed here in a previous article. With the changes Apple has made, and which seem to be coming in future releases of macOS, if the internal drive fails, the machine will not be bootable at all, even from a complete clone on an external drive. Does that change mean clones are no longer useful? No, clones are still a good option for backups. In comparison to Time Machine backups, clones have full copies of the actual files, not links to unchanged files, so Finder can be more safely used to access the copies in the backups. And if you decide to use the archiving process offered by the clone software, you can even have a decent history of changes to files, albeit not as deep as Time Machine can make in the same drive space.
The goal of this article, as I said, is not to necessarily show deep details for the various products but just to show an overview. For more details on how they work go to the developer links provided. In general, though, you set up the clone by selecting the source and destination drives, or folders of the source drive, and how you want the clone to be made, within the software parameters. You can then either run the clone process manually or schedule it to run automatically. Each clone process is one-way, that is, the data moves from the source to the destination. To do a restoration, you run the clone software and make the “source” the drive with the backup data and the destination the location to which you want the files restored. But each is one-way.
A second type of backup is a synchronization. Much like how iCloud can synchronize Photos and files across your Macs and iDevices that share an AppleID account, synchronization software can synchronize files, folders, even drives, between the Mac and an external drive or even to an external service you might have for storage. In other words, these type products are bi-directional. You can make two places match, even if there are changes on each one. A backup by this type application is essentially a clone of the internal drive because in almost every case there won’t be changes on the backup.
One such product is Chronosync, by Econ Technologies (https://www.econtechnologies.com). In the case of Chronosync, it has the two-way sync. But in the case of backups, you select the source and destination and tell Chronosync to keep the two synchronized by scheduled or manual synchronizations. The beauty of synchronization is that in addition to making a backup, you can use it to keep multiple Macs in the same state. I used Chronosync, for example to keep a MackbookPro and an iMac synchronized for pictures. The pictures were in folders on the two machines and Chronosync was scheduled to run once a night to keep all pictures on both machines the same. A business could use a synchronization software to keep the product list and descriptions synchronized across all of the Macs in the business so that management only has to make the change once and that change gets synchronized automatically. Chronosync can do one-way synchronizations pretty easily, so a restoration from a backup drive in Chronosync is as easy as changing the direction of the synchronization and executing the process.
As I said earlier, this article isn’t about all the details of the various products. For that, go to the vendor websites provided above.
What are the advantages and disadvantages of these products over Time Machine? Well, Time Machine is basically free as it comes with macOS. The third-party products all have a cost, although SuperDuper! has a limited capability free version. Bombich offers a free 30 day trial of Carbon Copy Cloner and EconTech has a 15 day free version of Chronosync. You can try all three and decide which one best suits your needs.
What do I do? Well, I use Time Machine for a deep historical backup of each of the machines in my household. TM can store a lot of history in relatively small space, and so is useful for that purpose. I use a cloner to make other backups of both full drives and individual folders to external drives on each machine. Finally, I use a synchronization, as I said earlier, to do a third backup of my pictures between two external drives. All of that activity is scheduled to happen automatically because I have a lousy memory for things like that and that kind of thing is exactly what machines should be able to do on their own without me having to babysit. I can, in the meantime, get on with using the machine without having to think about backups or synchronizing.