Until 19 years ago, when Apple introduced Time Machine, and the following year started selling Time Capsules, most of those who used Macs made no regular backups. As the author of the Q&A pages in MacUser (the UK magazine), I had received a steady stream of questions about how to recover lost files that had never been backed up. By 2009, that had all but dried up as backups became commonplace, and many were implementing thought-out backup strategies.

Perhaps the first apparently naïve question is how can you back up your backups? How can you ensure that, should anything happen to your primary backup, there’s another backup you can rely on? Preferably one that will survive whatever minor or major disaster that might have lost access to that primary backup.

The bad news is that Time Machine backups made to APFS storage can’t be copied or backed up themselves, but that was also true in practice of their previous backups to HFS+. You can, though, copy backups made by several third-party utilities like Carbon Copy Cloner. Whether that should be a part of your plan is another matter.

Even the smallest computer system needs a backup strategy, a plan however informal that ensures you will never lose valuable or important files. The best way to develop that is to consider first what needs to be preserved in the event of a disaster, no matter its scale.

What needs to be preserved?

This varies enormously, but considering some potential disasters should give you a good start. How would you cope if your Mac suddenly died, and had to be replaced? Most of us would like to be able to restore or migrate pretty well everything that was on our old Mac to the new one. You can only do that if pretty well everything is backed up, including the apps you use, apart from those bundled in macOS, and those you can download again from the App Store.

At the other extreme, what would you really need if your Mac’s location was destroyed by flood or fire, and you had to put things back together somewhere else? While it might be nice to have everything to hand, there’s a bare minimum of essentials like tax, financial and legal documents, and maybe those vital to your business or profession. Those need to be stored somewhere physically separate from your Mac, preferably where you can guarantee access in the future, whether it’s a cloud service or a safe containing archival storage media.

These will help you decide what needs to be backed up frequently, possibly hourly as Time Machine offers, and may have a relatively short lifetime, and those essentials that may not change as much, but need to be archived for longer or indefinite periods.

You should also allow for increasing quantities that need to be backed up and archived in the future. The chances of needing less seem remote, although there have been savings when progressing from scanned paper to fully digital documents.

Reduce risk

One fairly simple scheme to reduce the risk of data loss is to keep multiple copies in independent storage media. There are many ways to achieve that, including:

• RAID 1, or mirroring, where two or more exact copies of the same backups are stored on separate disks, normally in the same enclosure. This has been popular as a means of reducing risk when using relatively unreliable hard disks.
• Rotating independent backup storage for Time Machine. Although not widely used, Time Machine will automatically make alternate backups to multiple separate backup storage volumes. This is simple to set up, well-proven, and can be used to provide off-site backups as well. I have explained that and other features here.
• Two independent backup methods, such as hourly Time Machine backups to one disk, and nightly Carbon Copy Cloner backups to another. This has the virtue that simultaneous problems in both backups are significantly less likely.
• Although there’s nothing as convenient as Time Capsules, network storage in a NAS can bring the economy of scale for multiple users, and modern NAS systems can offer high performance with 5Gb and 10Gb ethernet, and NVMe SSDs.
• One or more on-site backups to local storage, and one to a cloud service. These are more resilient for storing backups off-site.
• Use iCloud data sharing in addition to, but not instead of, local backups. Syncing a replacement Mac to data shared in iCloud is a quick and simple way to gain access to your passwords, address books, calendars, etc., but you still need a fallback in case that’s not available.

Process and records

Businesses, however small, need to record details of their backup strategy. Although most private individuals don’t, you do need to plan and document for the ultimate disaster in which you can no longer be present. What if you were also a victim of that disaster? Would your next of kin know how to gain access to your backups and archives, particularly tax, financial and legal records? Apple provides details of how you can set up Legacy Contacts, as a good example of the planning you need to do.

Test and monitor

Some of the worst backup failures have occurred when backups were assumed to have been made correctly, but were left untested. When disaster struck, and the system manager went to restore from the backup, it was discovered that no intact backup was available because of a silent failure.

At least once a month, routinely check each of the backup systems you use, to ensure that a few randomly selected files can be restored correctly from the latest backup. This is a great confidence-builder, and essential if you are paying a cloud provider, for example.

Key points

• Everyone using computers or devices needs a backup strategy, even if it’s only informal.
• Decide what files need to be preserved using different backups and archives, to recover from different disasters, and allow for their growth in size.
• Reduce risk by using multiple backups, including separate and off-site storage.
• Time Machine backups to APFS can’t be copied or backed up, but in practice those to HFS+ normally couldn’t either.
• Document, including Apple Account Legacy Contact, for next of kin.
• Check each backup system at least once a month to verify you can recover files and restore from them.

I’m grateful to Franklin for prompting these questions.