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Mac Backup Strategy

I sometimes ask friends and family members about their backup strategies, a question usually met by sheepish looks and mumbled confessions of neglect. I tell them not to feel bad; the only reason I ask is because I don’t want them to make the same mistakes that I’ve made in the past.

This conversation is usually followed by me setting up an automated backup system for them. That doesn’t scale very well, so I have written this guide so folks can set it up on their own.

Formulate a Backup Strategy

The first step is to come up with a backup strategy. For me, that means a minimum of:

  • local bootable clone
  • local Time Machine backup
  • off-site backup

Having a bootable clone means that if your primary drive fails or gets corrupted, you can boot into your clone and be back up and running immediately, without any down-time.

Time Machine backups are not bootable, but they have something that the clone does not: versioning. If you delete an important file by accident and don’t immediately realize it, and your drive is replicated to your clone, then that important file will also be deleted from your clone. With Time Machine, however, you can go back in time and restore that deleted file.

The purpose of the off-site backup is geographical redundancy. If your home is burglarized or destroyed by fire, you could lose your computer and all your backups, with the important data within lost forever. That’s why off-site backups are an important pillar of any backup strategy.

Now that we delineated a backup strategy, let’s implement it.

What You’ll Need

  • the administrative password for your Mac
  • external drive at least as twice large as internal drive (this external drive will be completely erased)
  • SuperDuper (optional but recommended)
  • Arq
  • Backblaze B2 account

External Drive Partitioning

If you have one external drive at least as large as your internal drive, and you have another, second external drive that’s at least 1.5 times as large as your internal drive, then you can skip this section. Otherwise, you will need to partition a single external drive that is at least twice as large as your internal drive. In either case, this tutorial assumes all these drives do not have any valuable data on them, as they will be fully erased in order to store the backups.

macOS performs best when you leave at least ~20% of your internal drive free, as it is often used for virtual memory and other OS-level functions. Ergo, the following calculations are based on the assumption that the primary internal drive always has at least 20% of its capacity as free, unallocated space.

  1. Clone partition size = at least as large as internal drive capacity
  2. Time Machine partition size = multiply Clone partition size by 1.5


If you have a 500 GB internal drive, the above formula yields the following minimum partition size allocations:

  • Clone: 500 GB
  • Time Machine: 750 GB

With your external drive connected to your Mac and powered on, use the Finder to launch Disk Utility, which is in Applications > Utilities. Select your external drive from the list at left and then tap the Partition button in the top-hand toolbar. If the button is grayed out, make sure you have selected the drive and not the indented volume shown beneath the drive in the list.

Use the pie chart, plus sign icon, and other controls to create the two partitions (Clone and Time Machine), ensuring the capacities are calculated as noted above. Once everything looks right, and you are absolutely certain you do not have any data that will be lost, proceed by selecting the Apply button.

Partitioning should be a fairly quick process. When done, quit Disk Utility and proceed to setting up Time Machine.

Local Backups

Time Machine

Go to Apple Menu > System Preferences… > Time Machine and tap the Select Backup Disk… button. Choose the Time Machine volume from the list and then tap the Use Disk button.

That’s it. From now on, as long as your external drive is connected, Time Machine will automatically back up your internal drive every hour.

Clone Primary Drive

You can clone your drive via several methods, two of which are presented here. That said, I highly recommend you choose the first one, SuperDuper. Unlike the other method, SuperDuper can be set to clone on a consistent schedule, along with many other benefits. The developer works incredibly hard to make SuperDuper the best cloning product on the market; it is well worth the US$27.95 cost.

  1. Connect your external drive and rename it to: Clone

  2. Launch SuperDuper. Choose drives from the drop-down menus such that you see something like: “Copy (name of your internal drive) to Clone using Backup - all files”

  3. Making sure you are okay with your external drive being fully erased, tap the Copy Now button.

  4. Cloning will take a long time. When done, tap the OK button.

  5. Choose the Options button. From the During Copy drop-down menu, choose the item that starts with Smart Update… and then tap OK.

  6. Tap the Schedule button, choose a clone backup schedule that makes sense to you, and tap the OK button.

  7. Use Finder to locate your Clone external drive. Drag it to the Trash icon and let go to unmount it. Disconnect the USB cable from your computer.

Alternate Method: Clone via Disk Utility

This method is more complicated than using SuperDuper and requires booting into your internal drive’s recovery partition.

  1. Restart your Mac and immediately hold both Command and R keys until the Apple logo appears.
  2. When presented with a list of options, choose Disk Utility and then Continue.
  3. In the left-hand sidebar, select the Clone drive.
  4. From Disk Utility’s Edit menu, select Restore.
  5. From the sheet that appears, look for a drop-down menu next to “Restore from” and select your internal drive as the source.
  6. Tap the Restore button to begin cloning your internal drive to the external “Clone” drive.

Once the process is complete, tap Done to close the Restore sheet.

Stay Connected

One very important consideration to highlight is that both the Time Machine and SuperDuper-based backups can only occur when your computer is connected to the powered-on external drive(s). So if you don’t want external drive(s) connected and powered on all the time, you must figure out a way to remember to connect them periodically and let the backup processes run their course. Otherwise, all of this is for naught.

Off-Site Backups

Choosing an Off-Site Storage Provider

I chose BackBlaze’s “B2” cloud storage for the following reasons:

  • no minimum cost: only pay when data is stored/transferred
  • monthly storage cost is among the lowest at $US0.005/GB/month
  • data restoration cost seems reasonable and doesn’t feel punitive

If you are already paying for Dropbox, Google Drive, or another cloud drive product, or if you don’t have much data to back up and can get by with a free plan, then you might find that to be a good option. I don’t like the minimum cost “floor”, plus per-gigabyte overage model, associated with these kinds of products. Backing up 500 GB, for example, costs only $2.50 on B2 but $5 per month via cloud drive services.

But that’s just my suggestion. Feel free to read more about this in Arq’s section on Choosing a Storage Provider.

Install and Configure Arq

  1. Purchase, download, and install Arq. Launch Arq and choose what to back up from Backups menu > Add (Home) Folder to Backups…
  2. Choose B2 when prompted.
  3. Log into B2.
  4. When prompted, create and name a new bucket.
  5. Once provider has been set up, enter Arq license key.
  6. Add home folder (or other desired starting point); enter long passphrase when prompted and store in your password manager
  7. Edit backup selections to exclude any large files/folders that you don’t care about losing, if any (example: huge game files that you could easily re-install)

Once you tap the OK button confirm your backup selections, you should be all set. Arq will automatically encrypt and back up your data to B2’s off-site storage facility.

Final Thoughts

As someone who is no stranger to data loss, I know first-hand how painful it can be. While there is a small financial cost to implementing a backup strategy like this one, and it would be nice if it were a little easier to set up, the effort is 100% worth the peace of mind. Once it’s configured, this system hums along in the background and silently prevents the loss of priceless family photos, home videos, and other data you simply cannot affort to lose.

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