# Double fault when scrubbing ZFS



## ralphbsz (Apr 1, 2014)

Once every so often, my server at home crashes/freezing.  It always happens when scrubbing ZFS.  Today, for the first time, I managed to catch the console output (before that, it always happened during the day, and my wife and son would have to reboot before I got to it).  It's a double fault, meaning kernel bug.

This is a stock FreeBSD 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue Jan  3 07:15:25 UTC 2012 root@obrian.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386 

This being such an old version probably means that nobody is going to seriously look at it.  I'll post the details here anyhow, in case someone is amused by such things (in the Storage subforum, because it most likely is a ZFS problem).  Is there anything productive I can do?  Post it on the kernel bug list?  Set some debugging settings?  I know that the only way to fix the machine from crashing is to upgrade to a much newer version, but I just haven't had time for that in the last few months.


```
Fatal double fault:
eip = 0xc0d330f7
esp = 0xf53bcae4
ebp = 0xf53bcb20
cpuid = 0; apic id = 00
panic: double fault
cpuid = 0
KBD: stack backtrace:
#0 0xc0a4b157 at kbd_backtrace+0x47
#1 0xc0a186b7 at panic+0x117
#2 0xc0d489cb at dblfault_handler+0x9b
Uptime: 11d6h37m47s
Automatic reboot in 15 seconds - press a key on the console to abort
```

But the system actually hangs there, and never reboots.  And when I manually reboot it, the ZFS scrub that was in progress just restarts, and proceeds without any problems.


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