AIX Startup Process

Source: Internet
Author: User
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The startup process includes the following steps:

  • The initial step for starting a system is power on self test (post ). The purpose is to verify whether the basic hardware is working properly. Initialize the memory, keyboard, communication, and audio devices at the same time. All these devices are displayed on the screen. In this step, you can press the function key to select a different startup list. The LED values displayed in this phase are model-specific. Both hardware and software problems may make the system unable to start.
    Note: an additional step, called built-in self-check (built in self test, BIST), will be performed before the old system based on the MCI architecture ). This step is no longer required for Systems Based on the PCI architecture.
  • System read-only storage (ROS) is specific for each type of system. It is required to start AIX 5l Version 5.3, but it does not build the required data structure for startup work. It locates and loads Bootstrap code. The system Ros contains general startup information and is independent of the operating system.
  • The software ROS (also known as the boot program) forms an IPL control block, which is compatible with AIX 5l Version 5.3 and is used to receive control and build specific boot information for AIX 5l. A special file system is located in the memory and a file system named ramfs is created. Then, the software Ros locates, loads, and gives control to Aix 5l to start the logical volume (BLV ). The software Ros is based on computer-type AIX 5l information and is responsible for computer preparation so that it can start the AIX 5l kernel.
  • You can obtain a complete list of files contained in BLV from the/usr/lib/boot directory. The most important components include the following:
    • AIX 5l Kernel
    • Startup commands called during startup, such as bootinfo and systmgr
    • A simplified version of ODM. Many devices need to be configured before hd4 is available, so their corresponding methods must be stored in BLV. These devices are marked as basic devices in a predefined device (pddv.
    • RC. Boot script
  • Load the AIX 5l kernel and take over control. The system will display 0299 on the LED panel. All the preceding code is related to hardware. By configuring the device and starting the INIT process, the kernel completes the startup process. The LED code displayed in this phase is the general AIX 5l code.
  • So far, the system has detected the hardware, found BLV, created ramfs, and started the INIT process from BLV. Rootvg is not activated yet. From now on, the RC. Boot script will be called three times and different parameters will be passed each time.


Startup phase 1

In this phase, the following steps are performed:

  • The INIT process started from ramfs will execute the startup script RC. Boot 1. If the INIT process fails for some reason, the Code c06 is displayed on the LED display.
  • In this phase, the restbase command is called to copy some of the ODM images from BLV to ramfs. If this operation is completed successfully, the LED display displays 510; otherwise, the led code 548 is displayed.
  • After this operation is performed, the cfgmgr-F command reads the config_rules class from the simplified ODM. In this class, the device whose property is phase = 1 is considered as the basic device. The basic device is all the devices required to access rootvg. For example, if rootvg is located in a disk, all devices from the motherboard to the disk must be initialized. Call the corresponding method to activate rootvg in startup phase 2.
  • After the end of start phase 1, the bootinfo-B command will be called to determine the final start device. In this phase, the LED will display 511.


Startup phase 2

In startup phase 2, the parameter passed to the RC. Boot script is 2.
In this phase, the following steps are performed:

  • You can use a special version of The varyonvg command (ipl_varyon command) to activate the rootvg volume group. If the command is successfully executed, the system displays 517. Otherwise, the system displays one of the following led codes: 552, 554, or 556, and stops the startup process.
  • Run the fsck-F command to check the root file system hd4. This operation will verify whether the file system has been detached cleanly before the previous shutdown. If the command fails to be executed, code 555 is displayed.
  • Mount the root file system (/dev/hd4) to a temporary mount point (/mnt) in ramfs ). If this operation fails, 557 is displayed on the LED display.
  • Run the fsck-F command to check the/usr file system and load the file. If this operation fails, the LED will display 518.
  • Run the fsck-F command to check the/var file system and load the file. Run the copycore command to check whether a dump has occurred. If a dump occurs, copy the default dump device/dev/hd6 to the default copy directory/var/adm/RAS. Then, uninstall/var.
  • Activate the main paging space/dev/hd6 of rootvg.
  • Call the mergedev process and copy all/dev files in the RAM File System to the disk.
  • Copy all custom ODM files in the RAM File System to the disk. The two ODM versions in hd4 and hd5 are now synchronized.
  • Finally, mount the root file system in the rootvg (Disk) to the root file system of ramfs. The mount point of the rootvg File System has become available. Now, mount the/var and/usr file systems of rootvg to their normal mount points again.
In this phase, the console is unavailable, so all startup messages are copied to the alog. The alog command can be used to maintain and manage logs.


Startup phase 3

After phase 2 is complete, activate rootvg and perform the following steps:

  • Start the/etc/init process. It reads the/etc/inittab file and uses parameter 3 to call RC. boot.
  • Mount the/tmp file system.
  • You can call the syncvg command to start rootvg synchronization as a background process. Therefore, all outdated partitions in rootvg are updated. In this phase, the led code 553 is displayed.
  • In this phase, the cmdmgr command is called. If the system starts in normal mode, option-P2 is used to call the cmdmgr command. If the system starts in service mode, you will use option-P3 to call the cmdmgr command. The cmdmgr command reads the config_rules file from the ODM and calls all methods corresponding to phase = 2 or phase = 3. All other devices that are not basic devices are not configured here.
  • Next, configure the console by calling the cmdcon command. If stdout redirection is not set after the console is configured, the startup message is sent to the console. However, you can find all the missing messages in/var/adm/RAS/conslog. The following led code may be displayed:
    • C31: the console is not configured yet. Provides commands to select the console.
    • C32: the console is an LFT terminal.
    • C33: the console is TTY.
    • C34: the console is a file in the disk.
  • Finally, use the savebase command to synchronize the ODM In BLV with the odm in the/(Root) file system.
  • Start the syncd daemon and errdemon.
  • The LED display is disabled.
  • If the file/etc/nologin exists, delete it.
  • If a device in cudv is marked as missing, a message is displayed on the console.
  • The message "system initialization completed" is sent to the console. RC. Boot execution is complete. The process init will continue to process the next command in the/etc/inittab.

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