IBM AIX Continuous Availability Features - IBM Redbooks
IBM AIX Continuous Availability Features - IBM Redbooks
IBM AIX Continuous Availability Features - IBM Redbooks
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System dumps can also be user-initiated by root users. System administrators and<br />
programmers can generate a dump and analyze its contents when debugging new<br />
applications. The system dump is typically submitted to <strong>IBM</strong> support for analysis, along with<br />
other system configuration information. Typically, an <strong>AIX</strong> system dump includes all of the<br />
information needed to determine the nature of the problem. The dump contains:<br />
► Operating system (kernel) code and kernel data<br />
► Kernel data about the current running application on each CPU<br />
► Most of the kernel extensions code and data for all running kernel extensions<br />
<strong>AIX</strong> V6.1 also provides additional features to reduce the size of dumps and the time needed<br />
to create a dump. It is possible to control which components participate in the system dump. It<br />
may be desirable to exclude some components from the system dump in order to decrease<br />
the dump size.<br />
Note: As of <strong>AIX</strong> V6.1, traditional system dumps are always compressed to further reduce<br />
size.<br />
The dumpctrl command obtains information about which components are registered for a<br />
system dump. If a problem is being diagnosed, and multiple system dumps are needed,<br />
components that are not needed can be excluded from system dumps until the problem is<br />
solved. When the problem is solved, the system administrator should again enable all system<br />
dump components.<br />
<strong>AIX</strong> V6.1 provides also a live dump capability to allow failure data to be dumped without<br />
taking down the entire system. A live dump will most likely involve just a few system<br />
components. For example, prior to <strong>AIX</strong> V6.1, if an inconsistency were detected by a kernel<br />
component such as a device driver, the usual approach is to bring down and dump the entire<br />
system.<br />
System dumps can now be copied to DVD media. You can also use DVD as a primary or<br />
secondary dump device. Note that the snap command can use a DVD as source, as well as<br />
an output device.<br />
2.3.3 Firmware-assisted system dump<br />
Firmware-assisted dump improves the reliability of the traditional system dump by minimizing<br />
work done by the failing operating system.The idea is to freeze memory and reboot the<br />
system prior to dumping the memory to disk. Firmware-assisted system dump means an <strong>AIX</strong><br />
dump assisted by firmware, which is taken when the partition is restarting. The firmware is<br />
involved to preserve memory across the reboot, and eventually to save parts of memory and<br />
processor registers.<br />
Important: In <strong>AIX</strong> V6.1, traditional dump remains the default method for performing a<br />
system dump in all configurations.<br />
Firmware-assisted system dump should only be used if you are directed to do so by <strong>IBM</strong><br />
Service during problem determination.<br />
Selective memory dump is a firmware-assisted system dump that is triggered by (or uses) the<br />
<strong>AIX</strong> instance. Full memory dump is a firmware-assisted system dump that dumps all partition<br />
memory without any interaction with the <strong>AIX</strong> instance that is failing. Both selective-memory<br />
dump and traditional system dump require interaction with the failing <strong>AIX</strong> instance to<br />
complete the dump.<br />
24 <strong>IBM</strong> <strong>AIX</strong> <strong>Continuous</strong> <strong>Availability</strong> <strong>Features</strong>
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