Unix kernel File System / Stand Directory & Configuration

About HP-UX System Architecture


Here are some points to give you some idea about the HP-UX Architecture:

- The directory /stand will be created as separate mounting file system.

- /stand will always reside on the first logical volume on the boot disk.

- /stand directory contain the system kernel and I/O mapping files that are required at boot time.

- In addition, the directory also contain kernel configuration and generation files.



- If /stand is separate file system, an entry corresponding to this file system must be maintained in the
   file /etc/fstab.  

- This entry is created when HP-UX is installed and must be maintained.


HP-UX Recovery
For HP- UX system recovery, the following file may be needed to restore from the backup.
/stand/rootconf (you sould not delete and modify that file system)
/etc/fstab
/etc/lvmtab
/stand/ioconfig


HP-UX Kernel Reconfiguration

- The HP-UX kernel requires a rebuild whenever a new functionality is added or removed from the system.

- Kernel need to be update to reflect the removal.

- New functionality: introducing new patches, new component installation, add or removing the device drivers etc.

- The kernel require reconfiguration when you modify the location of the primary swap or add or remove a dump device.

- A dump device is a place on a physical disk that is used by the system to place a dump of the of the running kernel and memory image in case the system crashes.

Modifying Kernel Parameter

- When you are installing an application or database software, you required to modify one or more kernel parameter in order for the application and database software.

- Kernel parameter control the HP-UX kernel behavior.

Static and Dynamic Kernel Module

- Kernel can compose number of modules. Modules can be dynamic or static.

- Static modules required a kernel rebuild and subsequent system reboot to make effective.

- Dynamic modules atomically loaded into the memory when it is needed by the kernel and get unloaded by itself when no longer required.

- Dynamic modules are also referred to as a Dynamically Loadable kernel modules.


Static and Dynamic Kernel Tunable Parameter

- Tunable parameter can be static or dynamic. After verifying the value of a static parameter the kernel need to be rebuild and the server must be rebooted for the new value to take effect.

- A dynamic tunable parameter, does not require a server reboot after it is value altered.

Reconfigure HP-UX Kernel

1. Change the directory to the kernel build environment
    # cd /stand/build

2. Gather running kernel information using the system_prep command and save it to a file called system by specifying the –s option with the command.
    #/usr/bin/sysadm/system_prep –s system

The system file contain drivers, subsystems, and tunable parameter information

3. Use the kmsystem and kmtune command to view and modify the build.

Example:
kmsystem –S /stand/build/system –q token2
kmtune –s maxvgs –S /stand/build/system

- Execute the following to generate a new kernel after updating the system file with token2 module
  #mk_kernel –s ./system
 #kmupdate

Reboot the system ..................... It's Done........