My biggest complaints with the whole ecc versus non-ecc are:
1. Most people don't realize that non-ECC RAM can spell certain disaster.
2. Most people don't realize that non-ECC RAM can spell certain disaster for your backups.
3. Most people are trying to reuse some desktop hardware that is old(for various definitions of old).
4. Most people are not informed enough to realize that ECC RAM really makes a difference for reliability.
For #1 and #2, there's "ifs" attached. IF your RAM goes bad. IF you don't catch it the moment the RAM fails(which is impossible). IF your backups are "online"(that is, they aren't in a safety deposit box or equivalent).
If your RAM never fails, great. You can use non-ECC RAM and all will probably be just fine. But, how are you going to guarantee that your RAM never fails? Some manufacturer came out and said that statistically, 5% of RAM sticks out there fail every year. So if you have 4 RAM sticks, you have a 20% chance that one stick will fail in a given year. That's pretty nasty odds when you are trying to use RAIDZ2, which has a statistical chance of total pool loss of <1% per year.
So when people claim they did RAIDZ3 with non-ECC RAM I stop and ask myself what the f*ck they were smoking. You just took a pool that has something like <1% chance of being lost in a year, and made it 20% because of the RAM. Remember, it's about the weakest link in the chain, which means 20%(technically it's an equation that is more than the weakest link, but let's keep this simple). RAIDZ1 is something like 18%, and we don't recommend that stuff! So why the hell would we recommend non-ECC RAM.
So, strictly from a math numbers thing, RAIDZ1 = 18%, and 4 sticks of non-ECC RAM are 20%. So if you take these numbers as fact and have a choice between going with RAIDZ2 with non-ECC RAM or RAIDZ1 with ECC RAM, RAIDZ1 with ECC RAM is technically safer.
Statistically, there will always be people who "beat the odds". So freakin' what. Does that mean you should go gambling too? But, these people that beat the odds will never stop telling the world how awesome they are because they beat the odds. And they'll have no problem telling you that they did exactly what PersonX said not to do and that it worked for them(and therefore it MUST work for you). But, when it doesn't work for you, your data is lost. They'll shrug their shoulders, walk to the next guy, and start telling him how awesome they are because they beat the odds.
So if you wanna go with non-ECC RAM, do it. I double dog dare you. It's your win or your loss. The stupid shall be punished, and I won't miss any sleep with someone makes the wrong choice and loses their data. The only thing I *want* is for people to *know* about these potential pitfalls. If they know and still do it, that's fine. Their gamble and their data. My concern is for the people that *don't* know.
I'm through giving a sh*t about people that want to argue it. I'm not here to argue it. I'm here to inform. If you don't want to be informed, then don't read about it and keep doing whatever it is that you are doing. If you want to dismiss me as an uninformed idiot, that's fine too. I still won't care. But, I will gladly laugh at your demise when you lose your pool because of bad RAM. Not because I'm a jerk(I am a jerk.. but for other reasons), but because I told you so and you didn't listen.
