My kernel panics suck

Jeremy Chadwick freebsd at
Fri Jul 2 23:49:48 UTC 2010

On Fri, Jul 02, 2010 at 07:35:14PM -0400, jhell wrote:
> On 07/02/2010 16:29, C. P. Ghost wrote:
> > On Fri, Jul 2, 2010 at 9:18 PM, William D. Colburn (Schlake)
> > <schlake at> wrote:
> >> I got my new 8-stable system up, and now I just have recurrent disk
> >> controller failures.  The machine can't stay more than about ten
> >> minutes before it panics into a hung kernel, or simple reboots.
> >> Unfortunately, I know the root cause of the panics.  If my computer is
> >> sitting on the table, then the kernel doesn't panic.  If the computer
> >> is sitting on the desk, then it panics like mad.  The table is wooden,
> >> the desk is metal.  Of course, I'm also changing power too.  On the
> >> table, I use a wall outlet, while on the desk I use my Smart UPS.
> >> Unfortunately, you can't really help me with this.  I'm just writing
> >> in out of the hope that I'll get some sympathy for this problem.
> > 
> > Yuck...! If you have an electrical insulation problem, and your desk
> > is metal, I'd _really_ urge you to replace your hardware completely,
> > or have it properly insulated by a professional electrician. An electric
> > shock could cause real pain() and panic(). ;-)
> > 
> > But seriously, if that's the only reason for the panics, it's a pretty
> > strong hint that you have an electrical problem: when ICs  are
> > underpowered, they tend to behave erratically.
> > 
> >> -- Schlake
> > 
> > -cpghost.
> > 
> Adding to this, though I find it unlikely but worth mentioning but you
> could be grounding out to a already charged surface through a screw in
> the case (laptop/desktop), check the bottom and cover up anything you
> find with black electrical tape and try again. Another route would be to
> grab a multimeter and test the metal table for a positive ? source. If
> that metal table also happens to be screwed down to the floor then take
> all the screws out as one maybe more could be running across some weird
> current.

I'm a little surprised everyone's focused on the desk/grounding rather
than the UPS.  The OP doesn't state whether or not he's using a laptop
either (it matters).  I'm not denying improper grounding could cause
issues, but I'd expect to hear of the OP getting shocked or something
along those lines rather than "my storage controller acts silly".

Ripple or dirty power coming from a UPS -- because not all of them clean
things up -- could cause all sorts of chaos hardware-wise too, and in
some cases permanent damage.

| Jeremy Chadwick                                   jdc at |
| Parodius Networking              |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |

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