How to trigger a live crash dump
A less known option of this command it the
-L option. With this option you can command the system to create a live crash dump. The system isnīt paused while creating the dump, so the live crash dump isnīt self-consistent (the state of the system at the end of the creation may be different than the one at the beginning of this process. Nevertheless a live crash dump is still a useful toll. Triggering the crash dump is really easy as the following example shows.
# savecore -L
dumping to /dev/zvol/dsk/rpool/dump, offset 65536, content: kernel
100% done: 155962 pages dumped, compression ratio 3.32, dump succeeded
System dump time: Mon Dec 29 22:13:41 2008
Constructing namelist /var/crash/central/unix.0
Constructing corefile /var/crash/central/vmcore.0
100% done: 155962 of 155962 pages saved
After the creation of the crash dump you can analyse it with the standard toolset like the
mdb:
# mdb /var/crash/central/unix.0 /var/crash/central/vmcore.0
mdb: failed to read panicbuf and panic_reg -- current register set will be unavailable
Loading modules: [ unix genunix specfs dtrace cpu.generic uppc pcplusmp scsi_vhci zfs
ip hook neti sctp arp usba uhci fctl sd md lofs audiosup fcip fcp
cpc random crypto smbsrv nfs logindmux ptm ufs sppp nsmb ]
> ::ps
S PID PPID PGID SID UID FLAGS ADDR NAME
R 0 0 0 0 0 0x00000001 fffffffffbc29c30 sched
[...]
R 7 1 7 7 0 0x42000000 ffffff00c5c42188 svc.startd
R 418 7 418 418 0 0x4a004000 ffffff00ca5a0018 ttymon
R 391 7 391 391 0 0x4a014000 ffffff00cd995e08 sac
R 395 391 391 391 0 0x4a014000 ffffff00cd9938e8 ttymon
>
This enables you to analyse the state of your system without having to aim for a moving target.
Itīs getting warmer, so this tutorial is a little bit shorter. Itīs about the a really hated topic: Panics, crash dumps, core dumps and the tools to manage and leverage this the informations resulting from this functions: Part 1: Introduction Part 2:
Tracked: Dec 29, 22:36