You’ll know ECC works when it matters; When you encounter a flipped bit. With an 8TB RAID, that is likely to be within the next 24 months. Go with option 1, an

You’ll know ECC works when it matters; When you encounter a flipped bit. With an 8TB RAID, that is likely to be within the next 24 months. Go with option 1, and Raid-Z2+. With RaidZ2, you’ll be able to not only detect but correct a flipped bit - Even if that flip happens when writing out the data. Pay attention to the counters. Your ZFS scrubs will report how many resilvers they have. You’re likely to encounter 1 in a scrub. You’re unlikely to encounter more than 2. If you see that, that’s when you check for memory errors. A single bad sector is likely the hard drive. Even a single flipped bit is likely a transient error; It could be your memory, or your disk, or anything in between. It happens at scale, and 8TB, read repeatedly, is a lot of bits. Look into rasdaemon and memtest86 - They’re the tools you use to debug what happens when The other advice I can give you: Don’t be paranoid. Your photos are likely to acquire bit rot. You will have dozens, even hundreds of bit flips that will happen in your lifetime. Of the many thousands of photos you will take, the chances that you will ever notice the discoloration or bad line that a bit flip will have in a photo are pretty small. Bit rot happens. Your photos are important to you, and you should treasure them, but treasure them for what they are: Things that you protect and are under your care, not things that must be twenty nines of correct. You can realistically achieve 10, even 12 nines of correct reads on your data. You don’t need more.