Ohio University

Recovering From a Failed ZFS Root Mirror Disk

Hypothetical. Say, for example, you’ve got a ZFS mirror on disk0 and disk1, from which your Nexenta system boots. A year or two later, disk0 crashes, and starts spewing messages such as the following:

 ahci: [ID 860969 kern.warning] WARNING: ahci0: ahci_port_reset port 0 the device hardware has been initialized and the power-up diagnostics failed

Shortly thereafter there’s a storm and the power goes out for several hours and drains your entire humongous UPS, and when the power finally comes back on, the system won’t boot — it stops at the grub prompt; issuing a standard boot command fails.