RAIDZ1 failure: FreeBSD/x86 boot Default: zroot/ROOT/default:/boot/kernel/kernel boot: ZFS: i/o error - all block copies unavailable Invalid format Can't find /boot/kernel/kernel RAIDZ2 failure: No. Boots fine. RAIDZ3 failure: No. Boots fine. Stripe & Mirroring boot fine. There's some error when changing from RAIDZx to Mirroring and choosing 2 disks - autoZFS fails to partition. Probably ZFS-sys counts all existing disk and fails due to uncleared disks left, misunderstanding 2 chosen and cleared vs. left with uncleared zroot from previous RAIDZx partitioning. So it turns out that ZFS counts & reads all disks, whatever quantity chosen in menu. It's failure misbehaviour. 5x 16Gb disks via SAS lsilogic. i386 - the same RAIDZ1 failure. ZFS shows very low speed (amd64 1000-5000 files/sec, i386 50-100 files/sec). But three disks RAIDZ1 boots fine, 4 disks - boots fine. Why do 5 or 9 or more disks lead to failure then? RAIDZ2 and RAIDZ3 fails to boot when chosen 11 disks.
I'm not sure I understand you correctly, but I would not expect the installer to modify devices that weren't selected as install devices. I also would not expect the system to boot reliably if some of the disks (that were not modified during the installation) contain invalid boot code. It could be argued that the installer should warn about the issue but that's not really a ZFS-specific problem. To get the attention from the people working on the installer it might help to adjust the subject and to clarify the report.
If all of your disks arent accessible from your bios as bootable disks then when the loader comes to boot it will be missing disks hence in this situation it will to boot.
^Triage: I'm sorry that this PR did not get addressed in a timely fashion. By now, the version that it was created against is long out of support. As well, many newer versions of ZFS have been imported. Please re-open if it is still a problem on a supported version.