Technically (and non-technically) your data is not backed up, as a mirror is not a backup in any way, shape or form. I have already previously tried to explain why... it's because, by mere definition alone, a backup of a dataset that is stored on the primary information repository requires (!) to be stored on a secondary information repository that is (also by mere definition alone) separate from the primary one, and, in RAID, two members of the same RAID array can never be in two different information repositories at once. For this, at least one of both physical drives (each one of which is a member of the same RAID array) would have to be physically removed from the RAID array. So, specifically in this regard, RAID is merely equivalent to JBOD, as the "elsewhere" in "storing a copy of the data elsewhere" is not referring to "elsewhere within the same information repository".
In addition to the above, the two members of the same RAID array always ramain in the same information repository until at least one of both members is physically removed not just from the RAID array itself, but from the whole system that provides data access to this same information repository via (a) data connection(s). One example of a system that provides data access to a secondary information repository is a backup server.
Further, in a typical home network environment where the average user (who only has a basic skillset and knowledge) is running a NAS, the NAS neither is a secondary information repository nor can be considered a part thereof. That's just because in such an environment the connection method or infrastructure used to hook up the NAS is typically not technically materially capable to divide the primary information repository into one primary and one secondary information repository. Rather, it's just a primary information repository that spans multiple enclosures and that's it... full end of story.
To summarize, the word "adequate" doesn't actually even begin to apply. Those who keep saying that they only plug in their NAS each time when they run their next backup job typically are those who are simply forgetting the fact that their secondary information repository immediately ceases to exist the moment when they plug it back in. Each time when they do that, it effectively becomes part of their primary information repository (i.e., an expansion thereof) until the next time when they unplug it. Again, whether their NAS uses RAID or JBOD, doesn't make a single difference in that regard.
Finally, RAID 1 (mirroring) reduces fault tolerance, the main purpose of which is to minimize the downtime (another benefit being that data can be read simultaneously from multiple physical drives so the read performance goes up... albeit JBOD does not prevent one from reading data from multiple physical drives per se...). That is, if only one drive fails in a RAID 1 array that consists of two physical drives, the system still continues to function normally. Whereas if the RAID 1 array consists of three physical drives, two drives can fail at once (or only one drive can fail and, next, before the RAID has successfully been rebuilt, a second drive can fail) and so forth. Hot standby, or hot spares can optionally be used (if the hardware allows it) so that the RAID rebuild can be started automatically as opposed to can be started only after the manual intervention of replacing failed drive(s), and, adding more members to the RAID 1 array can be considered (optionally also) to further strengthen resilience against multiple drive failures. (There also exist other forms of data mirroring besides RAID 1, though.)
As an aside, similarly, if the system uses two hardware RAID controllers (or HBAs) instead of only one, which is only one (common) example of what is known as duplexing, then if only one hardware RAID controller (or HBA) fails, the system still continues to function normally also.
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My Computers
System One System Two
-
- OS
- 11 Home
- Computer type
- Laptop
- Manufacturer/Model
- Asus TUF Gaming F16 (2024)
- CPU
- i7 13650HX
- Memory
- 16GB DDR5
- Graphics Card(s)
- GeForce RTX 4060 Mobile
- Sound Card
- Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
- Monitor(s) Displays
- Sony Bravia XR-55X90J
- Screen Resolution
- 3840×2160
- Hard Drives
- 512GB SSD internal
37TB external
- PSU
- Li-ion
- Cooling
- 2× Arc Flow Fans, 4× exhaust vents, 5× heatpipes
- Keyboard
- Logitech K800
- Mouse
- Logitech G402
- Internet Speed
- 20Mbit/s up, 250Mbit/s down
- Browser
- FF
-
- Operating System
- 11 Home
- Computer type
- Laptop
- Manufacturer/Model
- Medion S15450
- CPU
- i5 1135G7
- Memory
- 16GB DDR4
- Graphics card(s)
- Intel Iris Xe
- Sound Card
- Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
- Monitor(s) Displays
- Sony Bravia XR-55X90J
- Screen Resolution
- 3840×2160
- Hard Drives
- 2TB SSD internal
37TB external
- PSU
- Li-ion
- Mouse
- Logitech G402
- Keyboard
- Logitech K800
- Internet Speed
- 20Mbit/s up, 250Mbit/s down
- Browser
- FF
it doesn't matter if its a Windows forum or a Linux forum.. there is a few keywords in IT that always get the avalanche in motion. 
Just click on 'unwatch' as I do for many tedious threads.
