> I've ran it for real. Once a few more background services start running, ZFS bogs down and keels over. I've had to reboot the NAS dozens of times because the entire filesystem had become totally unresponsive.

Was that an off the shelf NAS? If so then I'm guessing it wasn't exactly high spec'ed even putting aside the RAM? eg did it have a 32bit CPU? I've heard that does a massive amount to dent ZFS's performance (I wouldn't know because I've only ever ran on it 64 bit systems).

As I said, I've not had any issues with raidz2 on 2GB RAM. I've even ran virtual machines on one OpenSolaris box with ZFS and 2GB RAM so these weren't always dedicated storage servers either.

edit: just read elsewhere you were running FreeNAS on a Pentium 4. Yeah that would do it. FreeNAS wasn't optimised for low end systems (in fact they outright tell you not to!) and the P4 is pretty low end CPU as well. I still think ZFS would have ran on that but you'd have been better off going with vanilla FreeBSD instead.

> Which is not an accaptable answer to the situation I presented, you still have to buy multiple disks to grow the pool, you can't do it one at a time.

...but you can't do that with most traditional RAIDs either and the few you can do it on require you to take the whole storage pool offline while you grow the pool then resize the file system. That process can literally take several days on some storage servers. So ZFS might require you to add vdevs to the pool (tank) but at least it can all be done on live systems without any downtime. That in itself is a massive boon for ease of use in my opinion.

To be honest, it's pretty rare you want to upgrade a storage array by just one disk anyway. At least outside of home users anyway. And if you are the type of person that would need to do that then you wouldn't go for a traditional raid5/6 style pool either. Thus the argument becomes a comparison of apples and oranges as you'e comparing completely different types of software RAIDing.

> Not only unraid

I didn't say "exclusively unraid". I said "solutions like unraid". I'm fully aware there are other solutions out there.

> there are other systems that provide almost this. Syno and QNAP can both grow an array in storage capacity if you add a single new disk, even if it's larger and once you have added enough to provide parity, the additional capacity will become used too.

When you said "there are other systems that provide almost this" and "once you have added enough [disks] to provide parity, the additional capacity will become used too." I really had to question what your actual point of this discussion was because just a paragraph earlier you were calling my points "unacceptable" because ZFS required you to add more than 1 extra disk to provide parity; and now you're saying your preferred solutions also does the same?

I hope I'm just being presumptuous here but it's starting to feel like you're just arguing for the sake of arguing. :-/

> I found the commands anything but intuitive though I guess that's a difference of a few years of experience

Maybe. I've been a Linux and UNIX sysadmin for a fair few years now so experience is not something I'm short of. :)

Honest question: what is your experience of ZFS outside of the troubles you had on your NAS? I could totally see why the problems you described would taint your opinion of ZFS but I definitely wouldn't say what you experienced is typical for ZFS.

In any case, I'm not going to argue that everyone should be running ZFS - it's just technology, you can run whatever you want to run.