Ok gents, I got some info from a higher source.
The P20 stuff has been tested in the burnin lab at iX for almost a year. So I'd say "yes, it's been tested on hardware we recommend" and vendor specific stuff may or may not be as 'friendly'. If the P20 stuff freaks you out (and frankly I wouldn't be surprised considering the problems we've had with P16 driver with p20 firmware) then stay on P16 and don't upgrade to 9.3.1 yet. I'm not particularly worried about P20 firmware, with one exception.
P20 has had 3 'versions'. As of this writing the current is 20.00.04.00 and was released on May 21, 2015. There are other versions of 20.00.0x.xx out there. The driver that FreeNAS uses is 20.00.04. In an ideal (and most stable world) you'd want the 20.00.04 driver and firmware. I'm not privy to exactly what was changed, but I've heard through the grapevine that you'd ideally want to be on this latest build and not one of the p20 builds from prior as they have problems. I don't know how big of a deal the problems are for those of us that don't use the RAID function, but I prefer to be safer than sorry.
Here's where things get a little more confusing (yeah, I'll probably do an article on this to clear everything up). Supermicro hasn't provided the p20 firmware with their lsi sas 2008 on-board chips. You can upgrade these using the LSI/Avago stock firmwares. But you have to use specific firmwares. I want to confirm the exact matches before I publish these for the world as I'd rather not provide incorrect info.
In short:
- If you've been on 9.3.0 and p16 firmware and don't have onboard SAS chips, feel free to upgrade to 9.3.1 and flash the p20 firmware (download it from LSI and not elsewhere so you are sure you have the latest build). The risk of problems with p20 drivers and p20 firmware is very low.
- If you've been on 9.3.0 and p16 firmware and have onboard SAS chips that are have p20 firmware and the firmware is from May 2015 or newer, feel free to upgrade the LSI firmware and FreeNAS to 9.3.1. From the information I have the 'big ones' that don't have p20 official firmware are Supermicro boards with the LSI 2008 chipset and AsRock Rack motherboards. I have no ETA on AsRock Rack's release schedule, but apparently running P20 has been unstable for some people. Since AsRock Rack hasn't updated their firmware to P20 yet I have no idea what that means. I'll see what I can found out.
- If you've been a bad boy and have been using p20 firmware all along, you should upgrade to the latest p20 firmware and upgrade to FreeNAS 9.3.1 as soon as possible. P16 drivers and P20 firmware is a recipe for problems. Since it has been discussed in depth many times before I won't bother with any more on the topic.
- I definitely wouldn't recommend people upgrade to FreeNAS 9.3.1 and keep the p16 firmware though. If you don't see a P20 firmware for your hardware, don't upgrade to 9.3.1. Contact your hardware vendor and find out what the solution is. They may be releasing a p20 firmware soon.
- If this stuff freaks you out... just don't upgrade. 9.3.1 is new, and people are still working on getting familiar with the added features, bug fixes, etc. It's not the end of the world to wait a week or two for things to be a little more comfy.
You could have (and still can) upgrade from the shell. The main reason why we haven't generally recommended upgrading from the shell is because there's no telling what will happen to your zpool during that period between when you start the upgrade process and actually reboot. There's *going* to be a period of time where you will be on one driver and a different firmware. So it was about mitigating the problems.
I, personally, don't recommend upgrading from the shell because of all of the possible variables involved. TrueNAS does it automatically. When you upgrade a TrueNAS system, the LSI firmware is included and upgraded accordingly. But TrueNAS hardware is very specific, very heavily tested, etc. When dealing with FreeNAS it's random hardware put together by someone that may or may not have chosen good components, may or may not have customized the OS, and may or may not have other unknown problems.
As always though.. keep a backup. :)