Friday, April 25, 2014

Boot Process on Redhat

            Boot Process in RHEL LINUX

1 POST(Power on Slef test is run) - which check for hardware devices which are connected physically

2 MBR(Master Boot Record) - i.) Loads Boot Loader
               ii.) Read Grub information
              iii.) Stage 1 - checks for OS installation through CD/DVD
               iv.) stage 2 - Checks for /boot Partition, Check VMlinuz(kernel file), check initramfs
                initramfs = it is a image which loads basics drivers of devices into kernel

3 Kernel Initialization - initiates files
               i.) /etc/sysinit
              ii.) /etc/fstab     - File system is checked,if corrupted or not
             iii.) /etc/hosts     - looks for hostname
              iv.) /etc/resolv.conf - DNS configured or not
               v.) /etc/sysconfig/network-scripts/eth0 - check for IP information
               vi.) /etc/sysconfig/network
             vii.) /etc/inittab     - to check runlevel

4 Run Level        - /etc/rc.d/rc0.d
            - /etc/rc.d/rc1.d
            - /etc/rc.d/rc2.d
            - ---------------
            - /etc/rc.d/rc6.d

5 Service Startup Phase - /etc/init.d    - All the service are checked , Running etc.

6 Run Customized Scripts- /etc/rc.local

7 Terminal Startup    - /etc/init/tty.conf    - It will look for Virtual Terminal [ALT+CTRL+F1.....F7]

8 Login            - /etc/passwd

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