Solaris 10 10/08 Release Notes

Taking the Primary Disk Offline in a Mirrored ZFS Root Pool

Do not take the primary disk offline in a mirrored ZFS root configuration. The system will not boot from a disk taken offline in mirrored root-pool configuration.

Workaround: To detach a mirrored root disk for replacement or take it offline, boot from another mirrored disk in the pool. Choose one of the following methods: