How to back up large files and collections off site

Mark Weinrib writes in with a question about his 500GB iMovie Library file, which he has stored on an external drive.

I back it up using Time Machine, but I would like to have another backup option. I don’t have 500GB free space on my Mac, so Dropbox doesn’t look like an option. iCloud Drive has a 15GB limit on file size so that won’t work.

The iMovie Library file is really a package: a sort of folder that contains stuff you don’t typically need to access directly, and which should move together whenever you need to move the main file. So iCloud wouldn’t count it as one monolithic 500GB file, but rather would handle each component as a separate piece.

However, I don’t think iCloud is the right option for this kind of backup. iCloud works best for items you want to sync across devices and make accessible to each, rather than as a back up in case of failure. Dropbox has the same orientation as a service and the same weakness. (If you want to use the iMovie Library with different Macs, an external drive is the way to go, and cart it around to different machines.)

More generally, if you’re trying to just making an archive copy of a lot of data that you can restore in the event of an emergency, you could pursue one of a few different options:

• Rotate Time Machine drives off site. Get a second drive to use for Time Machine backups, and store the one not in use in a safe-deposit box or in another secure location. At intervals, every few days or weeks, swap the drives. Time Machine will always make an up-to-date backup for any volume marked for backups when you reattach it to a Mac.

• Copy to a friend’s computer via CrashPlan. If you know someone with whom you could trade offsite backup who has some spare hard drive storage or where you could stash an extra drive, you can use CrashPlan’s Mac software at no cost for encrypted peer-to-peer backup. CrashPlan’s software can be funky, as it relies on Java. Both you and your friend need to run the software. (You don’t have to install Java to use it, however, and it doesn’t make your system vulnerable to Java exploits via the Web.)

• Use a hosted-backup service that lets you store your data in the cloud and automatically updates it. I wrote a run-down at PCWorld of the best options for encrypted backups for macOS (and Windows) that automatically update as you make changes to your files. This would work for your single large file but also any other data you chose, too, of course. I backup over a terabyte of data to CrashPlan.

• It requires more effort and expertise, but you can create a cloud storage account at Amazon or Google, and use a file-transfer or sync program to make backups. Amazon’s Simple Storage Service (S3) and Google Cloud Platform let you store large amounts of data very cheaply if you don’t need to retrieve it often. With the cheapest storage option, you can keep 500GB on Amazon S3 Glacier for $2 a month and with Google Storage’s Coldline flavor for $3.50 a month. Retrieval fees can wind up higher than storage fees, however, and there are also some small costs to upload files. Use the services pricing calculators to sort this out.

With Google and Amazon storage, you can set a note to copy files manually or use software to automate it. For manual copying, Panic’s Transmit file-transfer program ($34) works with Amazon S3, while CyberDuck (free, donationware) handles both S3 and Google Cloud Storage, while also offering encryption options for both services. The latest version of ChronoSync ($50) from Econ Technologies allows automatic, recurring sync to Amazon S3 and Google Cloud Storage that just pushes updated files.

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