Eight questions about data integrity, bit rot, and backups

Tech Support
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Q1:

Does macOS provide tools to monitor or to chech data integrity? That is, does it provide tools to monitor or to check whether bit rot occurred? (Maybe S.M.A.R.T or something like this.)

Q2:

Does NAS provide such tools?

Q3:

Does temperature fluctuations and humidity affect SSDs?

Q4:

Does modern NAS use SSD? Or they use HDD?

Q5:

I heard that even if your SSD die, you’ll be able to access your data (though this can be very difficult). Is it true?

Q6:

Regarding NAS:

  • Should I prefer 1a) RAID5, or 1b) RAIDZ1, or 2a) RAID6, or 2b) RAIDZ2, or 3) RAIDZ3, or 4) something else?
  • RAIDZ (that is RAIDZ1, RAIDZ2, RAIDZ3) are ZFS-specific RAIDs. Is it safe to store my APFS (Apple File System) data on ZFS? For example, since APFS use alternate data streams extensively (e.g., to store metadata, such as Finder color tags), I somewhat concerned they might be lost during APFS → ZFS → APFS transition.

Q7:

NAS vs. USB-or-Thunderbolt-or-FireWire-connected-SSD. Which option is better, and why?

Q8:

Apple does provide many storages: Storage - Mac Accessories - Apple

Other useful links:

Which one of them is best to use with Time Machine to backup my Mac?

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I’ll try to answer a couple of these.

Q1 Verify that a disk image’s data isn’t corrupted using Disk Utility on Mac - Apple Support

On second read that link isn’t as useful as I thought. One check you can do in Disk Utility is performed by selecting each drive and clicking on Get Info.

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Q4 Yes, some can use either or both

Q5 It’s possible depending on the damage and, IMO, it can be prohibitively expensive for most individuals. I used Drive Savers three or four times between 1999 and 2018. Seems like the cost of recovering a 4GB SCSI drive was around $2500 in the early 2000’s.

Q8 I don’t generate a ton of data these days so I prefer Samsung SSDs for local backup. I do have a lot of experience with Time Machine and no longer use it. TM has been discussed several times on this forum, you might find some of them informative.

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