In addition to booting from firmware-inaccessible storage devices, some new servers provide the ability to use a fallback image if the boot pool is unavailable. The fallback process depends on a small version of the Oracle Solaris OS, called a miniroot, that is stored on one or more service processors. The servers are preconfigured with fallback images. If you need to update the fallback image, see How to Update the Fallback Image.
During the fallback boot process, once the kernel from the miniroot is loaded, the root device is configured. This configuration includes a pointer to the location of the root pool on the iSCS device. Next, the root pool is imported and the boot archive is loaded into retained memory. The system is then rebooted from the boot archive and the boot process repeats, starting with loading the kernel. However the kernel in the second boot is from the boot archive, not from the miniroot in the fallback image.
The following figure shows this process.
Figure 2 Fallback Boot Process