The sysdumpstart command

The sysdumpstart command provides a command line interface to start a kernel dump to the primary or secondary dump device. When the dump completes, the system halts. Use the crash command to examine a kernel dump. Use the sysdumpdev command to reassign the dump device.

The sysdumpstart command syntax is as follows:

sysdumpstart { -p | -s [ -f ] }

During a kernel dump, the following values can be displayed on the three-digit terminal display as follows:

0c0 Indicates that the dump completed successfully.

0c1 Indicates that an I/O error occurred during the dump. This value only applies to AIX Version 4.2.1 or later.

0c2 Indicates that the dump is in progress.

0c4 Indicates that the dump device is too small.

0c5 Indicates a dump internal error.

0c6 Prompts you to make the secondary dump device ready. This value does not apply for AIX Version 4.2.1 or later.

-p Device Temporarily changes the primary dump device to the specified device. The device can be a logical volume or a tape device. For a network dump, the device can be a host name and a path name.

-q Suppresses all messages to standard output. If this flag is used with the -l, -r, -z, or -L flag, the -q flag will be ignored.

-r Host:Path Frees space used by the remote dump file on server host. The location of the dump file is specified by the path.

-s Device Temporarily changes the secondary dump device to the specified device. The device can be a logical volume or a tape device. For a network dump, the device can be a host name and a path name.

-z Determines if a new system dump is present. If one is present, a string containing the size of the dump in bytes and the name of the dump device will be written to standard output. If a new system dump does not exist, nothing is returned. After the sysdumpdev -z command is run on an existing system dump, the dump will no longer be considered recent.

Flag Description

0c7 Indicates that the dump process is waiting for a response from the remote host.

0c8 Indicates that the dump was disabled. In this case, no dump device was designated in the system configuration object for dump devices. The sysdumpstart command halts, and the system continues running.

0c9 Indicates that a dump is in progress.

0cc Indicates that the system switched to the secondary dump device after attempting a dump to the primary device. This value only applies to AIX Version 4.2.1 and later.

The sysdumpstart command flags are listed in Table 5-8.

Table 5-8 Commonly used flags of the sysdumpstart command

5.10 Quiz

The following assessment questions help verify your understanding of the topics discussed in this chapter.

1. Using the following error log entries as shown, which of the following conclusions best explains why the system crashed?

A. The system crash was caused by a signal 11.

B. The calc command caused the system to crash.

C. The system crashed due to an invalid inode number.

D. The system took a dump to paging space after the calc command core dumped.

Flag Description

-f Suppresses the prompt to make the secondary dump device ready.

This flag does not apply to AIX Version 4.2.1 or later.

-p Initiates a system dump and writes the results to the primary dump device.

-s Initiates a system dump and writes the results to the secondary dump device.

Figure 5-3 Error log case study

2. Which of the following crash subcommands should be used to verify the date and time of a system dump?

A. le B. t -s C. stat D. errpt

3. After a legacy microchannel system has gone down with flashing 888s, which of the following procedures is the best way to diagnose the problem?

A. Turn the power off and back on.

B. Reboot the system in maintenance mode.

C. Turn the key to service and press the Reset button to make a dump.

D. Verify that the key is in normal mode and press the Reset button to obtain error codes.

4. All of the following are contained in a system dump except:

A. The entire contents of memory B. The history of kernel function calls C. The process/thread that was active

D. The final history of error log events leading up to the system crash 5. Which of the following devices is a valid primary dump device?

A. /dev/hd5 B. /dev/null C. /var/adm/ras D. /dev/paging00

6. A system dump must be performed in order to have a permanent snapshot of the current state of the system. Which of the following commands should be run?

A. snap B. crash C. sysdumpdev D. sysdumpstart

7. After a user initiates a dump request on an AIX system, the entry shown in Figure 5-4 on page 104 is recorded in the system's error log.

Figure 5-4 Case study

Which of the following conclusions can be drawn?

A. The dump request failed.

B. The dump request was initiated due to an invalid sequence number.

C. The dump request was partially successful.

D. The dump request was initiated due to a problem with the device with the major/minor numbers 10,1.

8. What does the LED c20 indicate?

A. A system dump failure.

B. A partial system dump.

C. A complete system dump.

D. The low level debugger is invoked.

9. If a system crashes and the LED c20 is displayed, what does this indicate?

A. A dump has been forced on the system.

B. The system has automatically crashed.

C. The kernel debugger has been invoked.

D. The system took a partial dump and failed.

10.Which of the following codes best indicates that a crash was caused by a software problem?

A. 888-102-000-0c8 B. 888-102-207-0c0 C. 888-102-300-0c0 D. 888-102-500-0c4

11.Which of the following codes best indicates that the crash was caused by a hardware problem?

A. 888-102-207-0c0 B. 888-102-300-0c4 C. 888-102-300-0c8 D. 888-102-700-0c0

12.Which of the following dump codes best describes the LED 0c2 condition?

A. Dump completed successfully B. Dump is incomplete

C. No valid dump device

D. User requested dump started

5.10.1 Answers

The following are the preferred answers to the questions provided in this section.

1. D 2. C 3. D 4. A 5. D 6. D 7. A 8. D 9. C 10.C 11.A 12.D

5.11 Exercises

The following exercises provide sample topics for self study. They will help ensure comprehension of this chapter.

1. Describe the different ways to start a system dump.

2. On a core dump, name the two ways that can be used to find the program that caused the core dump.

3. Briefly describe how the crash command can be used to analyze system dumps.