Today, when I reboot my freebsd server. Server can’t boot. The error message is

ZFS： unsupported ZFS version 5000 (should be 28)
can't find /boot/zfsloader

default: ssd::/boot/kernel/kernel

boot:
can't find /boot/zfsloader

The problem is caused by that after I update zfs version, I should update bootloader at the same time.

Fix it:

Download the latest Freebsd 9.1 current image. Note:if you are using the stable image, the bootloader in the image is still old and can’t support zfs 29.

Then use the image to boot the server, then enter ‘shell’,run below command for all boot disks:

#gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 mfid0

then reboot the server