A heck of a reply - thanks for this.
I'm ..... curious if I should upgrade to the beta after all.
Is it possible to change my train (yes) and switch to beta, then on next reboot, switch to the old version, if problems occur?
I recall changing train, being a real problem - does it lock out previous boot instances?
- Yes boot environment choice should be fine, even with trains changed
- It's zfs. Run "zfs snap -r <SYSTEM_POOL_NAME>@BeforeTrialUpgrade" and you'll always have your existing setup to revert to from single user mode, regardless of what the upgrade process does,
- You can always export the pre-upgrade config, clean install old version, reimport
- Config is a standard sqlite3 file anyway so any number of softwares on every platform can read and rewrite your more complex settings if required, any time, which you should never need. That could be useful if you make functional changes in 12 and later want to backport them to say 11.x for any reason, as there isn't a way to import a later config into an earlier version AFAIK if the config structure has changed.
- Backup existing config + secrets file, off the server, snapshot your existing system, switch trains and upgrade, and don't upgrade pool features.
- If you have spare disks, then an alternative is to mirror and split the system pool, or clean install and import your old config, and again don't upgrade pool features, leaving your current boot/system disks intact and unchanged. Any issues, swap boot disks back.
I would say, that at this point unless you have pressing need, I'd wait for RC1 - it's due out fairly soon and there are a few annoyances believed fixed in it that if you haven't already moved, it's maybe not as worthwhile moving to beta2 just to upgrade to rc1 2 weeks later. I upgraded early because there was a feature I needed badly enough for my pool to actually be reliable, that outweighed the annoyances. If that's not you, then I'd suggest maybe give it the extra couple of weeks till the rc. But if you want the new fun things enough, yes it's pretty safe.
Upgrade works, I did that initially with beta1. When beta2 happened I grabbed spare disks, downloaded the ISO, and clean installed and imported my backed up config. I figured after a few years, and changes in ZFS, let's give the system pool a clean start too. Both ways worked fine.