Unplugging disk under ZFS yield panic

[Charles Sprickman]

On Jan 11, 2012, at 4:43 PM, Fabian Keil wrote:

> Jeremy Chadwick <freebsd at jdc.parodius.com> wrote:
> 
>> On Wed, Jan 11, 2012 at 09:07:08PM +0100, Fabian Keil wrote:
>>> Gergely CZUCZY <phoemix at harmless.hu> wrote:
>>> 
>>>> I'd like to ask, whether it is normal behaviour when we're unplugging a
>>>> disk under a ZFS system then on the first write a kernel panic happened.
>>> 
>>> Sounds familiar. I currently have two PRs open for
>>> reproducible kernel panics after a vdev gets lost:
>>> http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/162010
>>> http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/162036
>>> 
>>> Note that the pool layouts are different, though.
>> 
>> Is this problem truly ZFS-specific?  I'd been tracking this problem for
>> years, and was told it was fixed:
> 
> I'm not saying that my problems are ZFS-specific.
> The backtraces mainly contain geom functions and no ZFS code,
> so ZFS might be the victim here.

Is there any relation between this issue and the "log_sysevent:
type 19 is not implemented" problem that happens on device
insertion/removal on 8.2?

http://lists.freebsd.org/pipermail/freebsd-fs/2011-June/011855.html

I still see that one on 8.2-STABLE from around 6/2011.  I initially
thought it was triggered by device failure or removal (even with
proper hotplug support), but I got hit by it last night when
inserting a new drive in a chassis that supports ahci/sata hotplug.
IIRC it's not a ZFS issue, ZFS just gets more spammy (well,
extremely spammy to the point the system can't do much else) about
reporting an issue with a device going away or being inserted.

Charles

> 
>> http://wiki.freebsd.org/BugBusting/Commonly_reported_issues
>> 
>> * Panic occurs when a mounted device (USB, SATA, local image file,
>>  etc.) is removed
>> 
>>  Workaround: Be sure to umount all filesystems before removing the
>>  physical device
>>  Partial fix: Committed to CURRENT (8.0) on/prior to 2008/02/21
>> 
>>  There is ongoing work to fully fix this problem, ETA 2009/02 
> 
> This is a different problem. It was even easier to reproduce
> and at least I haven't seen it since the fixes went in.
> 
> Fabian