# Double Fault After v10 Update, ZFS



## phroggie (Jul 6, 2014)

Background: I have been running FreeBSD 9 on a headless server in its current configuration without a problem for well over a year. A few weeks ago I upgraded to v10 and aside from the server "dying" (it responds to pings but no SSH, when I dig up a monitor and keyboard, no response) every three or four days in the middle of the night it was at least usable. I haven't had time to address that issue so I've been wishing on every falling star that some patch would magically make that problem go away.

Tuesday before last I ran `freebsd-update` and every startup since then fails with a "Fatal double fault" after 6s uptime. And then lather, rinse, repeat. The same thing happens when I try to boot in single user mode.

My setup is two mirrored 1.8T drives with a single ZFS partition on them. Following the various on-line instructions, I somehow got it set up and working over a year ago and never gave it any thought since then.

I was hoping there is some way to reinstall FreeBSD from an installation CD but I the choices I make seem to lead to the install program wanting to repartition stuff. And, to tell the truth, I'm not sure that would help. I also imagine that once I exit to the shell, there's some way to run some check on the ZFS partition (zpool scrub?) but I really don't know what steps I have to take to get to the point where that would work. Again, that's just my best guess what to do.

So please, anybody, what should I do?

Peace,
phroggie


----------



## wblock@ (Jul 6, 2014)

Please show the exact error and describe the computer hardware.  What model, how much memory, 32- or 64-bit?

Have you tested the memory?


----------



## phroggie (Jul 7, 2014)

The error is 

```
Fatal double fault:
eip -0xc0a6b7a6
esp = 0xc6629fc8
ebp = 0xc662a024
cpuid = 0; apic id = 00
panic: double fault
cpuid = 0
KDB: stack backtrace:
#0 0xc0af6f12 at kdb_backtrace+0x52
#1 0xc0abce21 at panic+0x121
#2 0xc0f9736b at dblfault_handler+0xab
Uptime: 6s
```

The computer is a 32-bit Celeron what-was-on-sale-at-Fry's-that-week motherboard/CPU combo with on-board VGA graphics. I think there's 2G of RAM. It has worked flawlessly for a lot more than a year and does boot up on the install CD. I didn't run any memory tests since I'm suspecting a software problem.

Peace,
phroggie


----------



## kpa (Jul 7, 2014)

Does the stack trace look the same every time? If it does the problem might be in software, if it's different every time the problem is very likely a hardware one.


----------



## wblock@ (Jul 7, 2014)

The reason to test memory is that it's easy.  Always do the easy tests first.


----------



## phroggie (Jul 12, 2014)

Greetings,

I tested the memory and it's fine.

The numbers vary from time to time but the double fault (which I still don't know what that is) occurs in the same place: while it's trying to mount my ZFS volume.

I also tried hooking up one of the drives to a USB adapter then using a Parallels virtual machine to boot off of it on my Mac. It also crashed while trying the ZFS volume.

Peace,

phroggie


----------



## phroggie (Jul 13, 2014)

Here's where I am:

I've unplugged the second hard drive.

I booted off the v10 install CD, exited to the Live CD and did zpool import -f zroot. The ls command lists all my data.

At this point, I have to believe that there are no hardware problems and that my primary problem stems from my performing freebsd-update back on June 30th. My ZFS volume must be fine except for the code it's booting off of.

So I'm back to my original question: how can I reinstall FreeBSD off the install CD?

Peace
phroggie


----------

