Crashdump is memory dump of the system during the crash/panic. This dump file will provide you the exact status of system when the system panic or crashed. So we can determine root cause for crash by analyzing this file.If you are not expert to analyze this ,you can raise the support case with oracle for analyzing it.
Dumpadm manages the following:
1. dumpadm enables you to configure the crashdump of the operating system.
2.Dump data stored in compressed format in a order to save disk space.
3.Saving crash dump files is run in the background when a dedicated dump device, not the swap area, is part of the dump configuration.This means a booting system does not wait for the savecore command to complete before going to the next step. On large memory systems, the system can be available before savecore completes
4.using savecore -L command we can capture the live machine crashdump.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.
To set the dump device,
root@solaris:/ # dumpadm -d /dev/dsk/c0t3d0s1 Dump content: kernel pages Dump device: /dev/dsk/c0t3d0s1 (swap) Savecore directory: /var/crash/ Savecore enabled: yes
To see the current dumpadm details:
# dumpadm Dump content: kernel pages Dump device: /dev/dsk/c0t3d0s1 (swap) Savecore directory: /var/crash Savecore enabled: yes Save compressed: on
To change the savecore directory, you can use the following command.
root@solaris:/ # dumpadm -s /var/crash/solaris Dump content: kernel pages Dump device:/dev/dsk/c0t3d0s1 (dedicated) Savecore directory: /var/crash/solaris Savecore enabled: yes
Dump device:– Any raw device.
Savecore directory:- The location where the crasdump will save.
Forcing a Crash Dump:
The -d flag to reboot, which forces the kernel to panic and save a crash dump.
# reboot -d Mar 12 11:31:08 arengz reboot: rebooted by root panic[cpu9]/thread=70bbcde0: forced crash dump initiated at user request 401fbb10 genunix:uadmin+55c (1, 1, 0, 6d700000, 5, 0) %l0-7: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
When the system reboots, savecore runs automatically to preserve the crash dump in a file.
Saving a Crash Dump:
To get the running machine crashdump without impacting the OS , use the following command. You must have the dedicated dump device to perform this. (Not the swap device.)
# savecore -L
If you are familiar with MDB utility you can use analysis crashdump using that.
Thank you for reading this article.
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