HPUX boot process

HPUX boot process explained. Learn which all processes happened in background while HPUX server boots.

Its not fully detailed boot process. Its very short form of things happens during boot. To make it understand and remember (for interviews) easily!

1) PDC (processor dependent code) gets executed

Checks CPU
Checks stable storage for boot path
Loads ISL utilities from leaf area of boot disk
Here you can halt boot using ESC key and can run PO, SEA commands.

2) ISL (Initial system loader) gets loaded

Read AUTO file default kernel
Load and runs HPUX from LIF area
Here you can halt boot process and boot system into single user mode. U can provide diff options to SSL i.e. kernal vmunix. Like hpux –is, hpux –lq, hpux –lm

3) HPUX loads (Secondary system loader)

Uses options and path names from ISL to load kernel
And by default loads vmunix

4) After kernel vmunix gets loaded –

Swapper daemon starts with PID 0
Kernel runs /sbin/pre_init_rc
Kernel calls /sbin/init
/sbin/init reads /etc/inittab and calls –

/sbin/ioinit – to scan hardware and build kernel io tree
/sbin/bcheckrc – to check FS listed in /etc/fstab
/sbin/rc – to start additional services like lp, cron, cde
/usr/sbin/getty – to start n show login prompt to user.

Please note that this is not exact hpux boot process. There are alterations depends on system being referred is PA-RISC or Itanium. This article gives fair idea about whats happening in background when HPUX boot happens.