Three phases available in BOOT Process
1. Ros kernel init phase
2. Base Device Configuration
3. System boot phase
1. Ros Kernel init phase (PHASE1)
A. Post (power on self test)
In this post it will do basic hardware checking
B. Then it will go to NVRAM and check the boot list for last boot device (hdisk0 or hdisk1).
C. Then it will check the BLV (hd5) in boot device.
D. Then it will check the boot image
E. Then boot image is moved to memory.
F. Then kernel will execute.
2. Base Device configuration (PHASE2)
A. Here cfgmgr will run for device configuration.
3. System Boot Phase (PHASE3)
A. Kernel will execute.
B. The paging space (hd6) will get start.
C. Then following file system will be mounted /, /var. /usr, /home. /tmp
D. Kernel start the init process, it will read the /etc/inittab file and execute the following process.
/etc/rc.boot,
srcmstr
/etc/rc.tcpip
/etc/rc.net
The above network related files /etc/rc.tcpip, /etc/rc.net, used to configure the ip address and routing.
E. Then it will start the system by default run level 2.
NOTE:
Run level 2: It contains all of the terminal process and daemons that are run in the multi user
environment. This is default run level.
/etc/inittab file contains four fields, 1. Identifier, 2. Command, 3. Action, 4. Runlevel
SAP Basis Administrator 