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Oracle Solaris Administration: Common Tasks     Oracle Solaris 11 Information Library
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Document Information

About This Book

1.  Locating Information About Oracle Solaris Commands

2.  Managing User Accounts and Groups (Overview)

3.  Managing User Accounts and Groups (Tasks)

4.  Booting and Shutting Down an Oracle Solaris System

5.  Working With Oracle Configuration Manager

6.  Managing Services (Overview)

7.  Managing Services (Tasks)

8.  Using the Fault Manager

9.  Managing System Information (Tasks)

10.  Managing System Processes (Tasks)

11.  Monitoring System Performance (Tasks)

12.  Managing Software Packages (Tasks)

13.  Managing Disk Use (Tasks)

14.  Scheduling System Tasks (Tasks)

15.  Setting Up and Administering Printers by Using CUPS (Tasks)

16.  Managing the System Console, Terminal Devices, and Power Services (Tasks)

17.  Managing System Crash Information (Tasks)

What's New in Managing System Crash Information

Fast Crash Dump Facility

Managing System Crash Information (Task Map)

System Crashes (Overview)

x86: System Crashes in the GRUB Boot Environment

System Crash Dump Files

Saving Crash Dumps

The dumpadm Command

How the dumpadm Command Works

Managing System Crash Dump Information

How to Display the Current Crash Dump Configuration

How to Modify a Crash Dump Configuration

How to Examine a Crash Dump

How to Recover From a Full Crash Dump Directory (Optional)

How to Disable or Enable the Saving of Crash Dumps

18.  Managing Core Files (Tasks)

19.  Troubleshooting System and Software Problems (Tasks)

20.  Troubleshooting Miscellaneous System and Software Problems (Tasks)


System Crashes (Overview)

System crashes can occur due to hardware malfunctions, I/O problems, and software errors. If the system crashes, it will display an error message on the console, and then write a copy of its physical memory to the dump device. The system will then reboot automatically. When the system reboots, the savecore command is executed to retrieve the data from the dump device and write the saved crash dump to your savecore directory. The saved crash dump files provide invaluable information to your support provider to aid in diagnosing the problem.

The crash dump information is written in a compressed format to the vmdump.n file, where n is an integer that identifies the crash dump. Afterwards, the savecore command can be invoked on the same system or another system to expand the compressed crash dump to a pair of files that are named unix.n and vmcore.n. The directory in which the crash dump is saved upon reboot can also be configured by using the dumpadm command.

For systems that have an Oracle Solaris ZFS root file system, dedicated ZFS volumes are used for swap and dump areas. See Managing Your ZFS Swap and Dump Devices in Oracle Solaris Administration: ZFS File Systems for more information.

x86: System Crashes in the GRUB Boot Environment

If a system crash occurs on an x86 based system in the GRUB boot environment, it is possible that the SMF service that manages the GRUB boot archive, svc:/system/boot-archive:default, might fail on the next system reboot. For more information about GRUB based booting, see Booting and Shutting Down Oracle Solaris on x86 Platforms.

System Crash Dump Files

The savecore command runs automatically after a system crash to retrieve the crash dump information from the dump device and writes a pair of files called unix.X and vmcore.X, where X identifies the dump sequence number. Together, these files represent the saved system crash dump information.

Crash dump files are sometimes confused with core files, which are images of user applications that are written when the application terminates abnormally.

Crash dump files are saved in a predetermined directory, which by default, is /var/crash/. In previous releases, crash dump files were overwritten when a system rebooted, unless you manually enabled the system to save the images of physical memory in a crash dump file. Now, the saving of crash dump files is enabled by default.

System crash information is managed with the dumpadm command. For more information, see The dumpadm Command.

Saving Crash Dumps

You can examine the control structures, active tables, memory images of a live or crashed system kernel, and other information about the operation of the kernel by using the mdb utility. Using mdb to its full potential requires a detailed knowledge of the kernel, and is beyond the scope of this manual. For information about using this utility, see the mdb(1) man page.

Additionally, crash dumps saved by savecore can be useful to send to a customer service representative for analysis of why the system is crashing.

The dumpadm Command

Use the dumpadm command to manage system crash dump information in the Oracle Solaris OS.

The following table describes dumpadm's configuration parameters.

Dump Parameter
dump device
The device that stores dump data temporarily as the system crashes. When the dump device is not the swap area, savecore runs in the background, which speeds up the boot process.
savecore directory
The directory that stores system crash dump files.
dump content
Type of memory data to dump.
minimum free space
Minimum amount of free space required in the savecore directory after saving crash dump files. If no minimum free space has been configured, the default is one Mbyte.

For more information, see dumpadm(1M).

Dump configuration parameters are managed by the dumpadm command.

How the dumpadm Command Works

During system startup, the dumpadm command is invoked by the svc:/system/dumpadm:default service to configure crash dumps parameters.

Specifically, dumpadm initializes the dump device and the dump content through the /dev/dump interface.

After the dump configuration is complete, the savecore script looks for the location of the crash dump file directory. Then, savecore is invoked to check for crash dumps and check the content of the minfree file in the crash dump directory.