Solaris Boot Phase – Complete Deep Dive

Solaris booting starts from firmware (SP/BIOS), goes through GRUB bootloader, kernel initialization, and ends in SMF milestones. Understanding each phase is essential for troubleshooting boot issues and recovering broken systems.

Solaris Boot Phases Explained

From power-on until login prompt, Solaris passes through six well-defined phases. Each phase can fail independently and is useful for troubleshooting.

1. Firmware Phase

2. Boot Loader Phase (GRUB)

3. Kernel Phase

4. SMF Bootstrap Phase

5. SMF Milestones

6. Multi-User Mode

Important Boot Troubleshooting Commands

Check boot messages

Boot messages are stored in /var/adm/messages and dmesg output.

boot-phase

solaris-lab

[root@solaris ~]# dmesg | more
root@solaris # grep -i error /var/adm/messages

Check SMF service failures

Use svcs -xv to check which service is preventing boot.

boot-phase

solaris-lab

[root@solaris ~]# svcs -xv

List boot environments

Boot environments allow safe rollback during patching.

boot-phase

solaris-lab

[root@solaris ~]# beadm list

Boot to previous BE from GRUB

Useful if current BE is corrupted.

boot-phase

solaris-lab

{0} ok boot -L
{0} ok boot BE_name

Check current milestone

Milestones represent boot targets similar to run levels.

boot-phase

solaris-lab

[root@solaris ~]# svcs milestone/multi-user-server

How SMF (Service Management Facility) Controls Boot

SMF Boot Logic

SMF imports repository → starts core services
Services have dependencies defined in XML manifests
If one service fails, milestone cannot progress
Run levels map to SMF milestones:
S → milestone/single-user
2 → milestone/multi-user
3 → milestone/multi-user-server

smf-check

infounix@prod

# Debug SMF services
[root@solaris ~]# svcs -xv

Common Boot Problems

Corrupted boot archive
SMF service dependency failure
Failed kernel driver load
Filesystem corruption (ZFS issues)
Wrong BE activated

terminal — bash

infounix@prod

# Rebuild boot archive
[root@solaris ~]# bootadm update-archive -v

Knowing these phases makes Solaris boot troubleshooting far easier.