A driver bug can sometimes render a system incapable of booting. By taking precautions, you can avoid system reinstallation in this event, as described in this section.
A number of driver-related system files are difficult, if not impossible, to reconstruct. Files such as /etc/name_to_major, /etc/driver_aliases, /etc/driver_classes, and /etc/minor_perm can be corrupted if the driver crashes the system during installation. See the add_drv(8) man page.
To be safe, use the beadm(8) command to make a backup copy of the root file system after the test system is in the proper configuration. If you plan to modify the /etc/system file, make a backup copy of the file before making modifications.
See Chapter 4, Administering Boot Environments in Creating and Administering Oracle Solaris 11.4 Boot Environments and Booting From a ZFS Root File System in Managing ZFS File Systems in Oracle Solaris 11.4 for detailed information.
If the system is attached to a network, the test system can be added as a client of a server. If a problem occurs, the system can be booted from the network. The local disks can then be mounted, and any fixes can be made. Alternatively, the system can be booted directly from the Oracle Solaris system CD-ROM.
When a system panics, the system writes an image of kernel memory to the dump device. The dump device is by default the most suitable swap device. The dump is a system crash dump, similar to core dumps generated by applications. On rebooting after a panic, savecore(8) checks the dump device for a crash dump. If a dump is found, savecore makes a copy of the kernel's symbol table, which is called unix.n. The savecore utility then dumps a core file that is called vmcore.n in the core image directory. By default, the core image directory is /var/crash/machine_name. If /var/crash has insufficient space for a core dump, the system displays the needed space but does not actually save the dump. The mdb(1) debugger can then be used on the core dump and the saved kernel.
In the Oracle Solaris operating system, crash dump is enabled by default. The dumpadm(8) command is used to configure system crash dumps. Use the dumpadm command to verify that crash dumps are enabled and to determine the location of core files that have been saved.