Originally published at: https://tidbits.com/2019/12/13/international-verify-your-backups-day/
What better day than Friday the 13th to check that your backups are actually working by restoring some critical files?
I’m pleased to say that my Time Machine backups were in full working order when I needed to restore some data back in January after the purchase of a new iMac due to my old one breaking down. I also have an online backup via Backblaze as added insurance.
How about Wednesday the 18th as a poor substitute? Booted to my CCC external drive so that I can do Clean Install on my internal hard drive. Boot was very slow but it got there.
There’s never a bad time to test. 
First boots are often slow, but it may be faster on a subsequent one. Though of course external drives are almost always slower than internal drives too.
My external firewire ssd is so much faster than my iMac internal disk that I now boot from the former and back up to the latter.
Hey, it’s Friday the 13th! Have you verified your backups today? We’ll assume that most are working, but let us know if you discovered a failure.
Great idea. Verified both my cloud and local Time Machine backups. The latter experience was a bit odd, but TM’s UI has always been a bit…unique.
When running through the backup date indicators (column on the right side of the TM window), at first nothing happened when I clicked on the BU from about a year ago. Uh, oh. So I tried something much more recent. The indicator for that BU date turned red when I pointed at it. Uh, oh again. But I went ahead and clicked, and that date’s window opened. So, I worked my way back in time. Every date indicator I pointed at was red, but every one of those dates’ windows opened. Finally got back to the original date I wanted, and now its indicator also turned red, and I was able to successfully restore a folder from that BU. Whew!
Not sure who thought using the color red to indicate an available backup was a good idea (like, how about green?), but the bottom line is I was able to verify TM is working properly.
I use Carbon Copy Cloner with the setting " Find and replace corrupted files: Once a week" that should – in my opinion – make sure that my backups work, right?
It’s a good step, but honestly, no. The only way to make sure your backups are working is to use them for the purpose they’re designed for—to restore. In an ideal world, you’d restore everything to a new drive to make sure it worked fully, but smaller spot restores should be generally good enough. Anything else is insufficient information to be certain that the backed-up data can be read and written.
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I am soo glad you posted this. Seems my migration to a new Mac Studio Pro a few months ago, didn’t migrate the TM setup or changed it to manually. It was doing TM locally but not to my TimeCapsule 4TB I have on the home LAN. And that over time, I’ve been backing up iPhone images/data via export in Preview to folders on a drive that was excluded from backups.
Yes, I use CCC to clone to a dedicated external, that is weekly. But now, I may have to open up the old TimeCapsule and replace the 4TB with a 8TB. Or, invest in a NAS like Synology and throw some 4TBs in as a RAID and get complicated.
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Welcome to the September 2024 incarnation of International Verify Your Backups Day, which is still entirely relevant since its initial publication in 2009.
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Is a restore likely to be usable or to fail without altering the original data? My concern would be that I restore something, it turns out to be unusable, and my original copy has been overwritten. Is this scenario unlikely to occur? (Or better yet, impossible?)
I claim that concern cannot be entirely brushed away – if the problem lies with the Mac you would actually be somewhat lucky since if the problem is the backup you would have just overwritten a working Mac with a broken backup. Not a problem if you have a second independent backup (that’s not also broken), but otherwise this could get uncomfortable.
But there’s a simple way out from all this. 
If you have a secondary Mac or an older Mac you can afford to screw up, that will let you thoroughly check your primary Mac’s backups (yes, there should be multiple) without even touching your primary Mac.
Apart from @Simon’s suggestion of restoring to a secondary Mac (or at least a secondary drive), my general point is that you only need to do some spot-check restores to a new location. It’s less likely that there would be sporadic problems in the backup, so what you’re verifying is that the overall backup and apps involved all basically work. I never recommend overwriting original data.
I do this fairly often* using my nightly Time Machine updates or weekly SuperDuper! backups.
And, once in a while, I’ll boot from an external backup just to see if it works.
*I sometimes get too aggressive in cleaning out files…
Thank you, @Simon. Yes, I have multiple backups.
That should be simple. The only problem is my OCD nature wanting to avoid putting yet another item in the Recent Items list, especially with the same name as something already there.