To be honest, it seems rather silly to go this deep into probability calculations when your N = 4 (hard drives). I can present numerous wildly-differing anecdotes about how single hard drives I have owned have fared. I have some drives that are 20 years old that still apparently work fine. I've had brand new drives silently corrupt sectors after less than a year in use. Trying to put hard numbers to the probability of failures is a fool's errand. Better to simply assume that components will fail over time, and architect your system to handle those failures gracefully.
That said, I actually agree with much of the final architecture decisions made by the author. BTRFS raid1 with an offsite copy in a geographically distant area is a pretty good solution for the average person's personal documents. Possible improvements would be:
- Multiple offsite copies in different locations
- Hardware diversity (differing models of HDD, host PC, power supplies, etc.)
- Staggered hardware upgrades on a 5-10 year cycle
What a long and convoluted way to arrive at the most obvious conclusion. Use redundant storage (mirrors) for important data and have backups (3-2-1 rule).
Don’t waste money on redundancy if your data can be easily reacquired.
The author explicitly mentioned syncing to his parents house. Even the "RAID is not backup" should be more nuanced IMO once you are talking about FS that supports regular snapshots.
To be honest, it seems rather silly to go this deep into probability calculations when your N = 4 (hard drives). I can present numerous wildly-differing anecdotes about how single hard drives I have owned have fared. I have some drives that are 20 years old that still apparently work fine. I've had brand new drives silently corrupt sectors after less than a year in use. Trying to put hard numbers to the probability of failures is a fool's errand. Better to simply assume that components will fail over time, and architect your system to handle those failures gracefully.
That said, I actually agree with much of the final architecture decisions made by the author. BTRFS raid1 with an offsite copy in a geographically distant area is a pretty good solution for the average person's personal documents. Possible improvements would be:
- Multiple offsite copies in different locations
- Hardware diversity (differing models of HDD, host PC, power supplies, etc.)
- Staggered hardware upgrades on a 5-10 year cycle
- Cold storage (offline) copy
What a long and convoluted way to arrive at the most obvious conclusion. Use redundant storage (mirrors) for important data and have backups (3-2-1 rule). Don’t waste money on redundancy if your data can be easily reacquired.
off topic but I really like the design of the site
The overall design is fine, but I find the writing style of “fully justified with no capitals” difficult to read for something of that length.
Instantly recognisable as Tufte
https://edwardtufte.github.io/tufte-css
A NAS is not a backup device.
The author explicitly mentioned syncing to his parents house. Even the "RAID is not backup" should be more nuanced IMO once you are talking about FS that supports regular snapshots.