disk "flipped" - a known problem?

[Fabian Keil]

Andriy Gapon <avg at FreeBSD.org> wrote:

> Today something unusual happened on one of my machines:
> kernel: (ada0:ahcich0:0:0:0): lost device
> kernel: (aprobe1:ahcich0:0:15:0): NOP. ACB: 00 00 00 00 00 00 00 00 00 00 00 00
> kernel: (aprobe1:ahcich0:0:15:0): CAM status: Command timeout
> kernel: (aprobe1:ahcich0:0:15:0): Error 5, Retries exhausted
> kernel: (aprobe1:ahcich0:0:15:0): NOP. ACB: 00 00 00 00 00 00 00 00 00 00 00 00
> kernel: (aprobe1:ahcich0:0:15:0): CAM status: Command timeout
> kernel: (aprobe1:ahcich0:0:15:0): Error 5, Retries exhausted
> kernel: cam_periph_alloc: attempt to re-allocate valid device ada0 rejected
> flags 0x18 refcount 1
> kernel: adaasync: Unable to attach to new device due to status 0x6

I believe I saw something similar when trying to forcefully
end the cam lockups reported in:
http://lists.freebsd.org/pipermail/freebsd-current/2012-October/037413.html

Detaching the disc drive caused /dev/cd0 to disappear as expected,
but reinserting the drive didn't bring cd0 back.

> It looks like the disk disappeared from the bus and then re-appeared on the bus,
> but not to the OS.
> 
> One of the partitions that the disk hosted was a swap partition and it seems to
> be the cause of some of the following consequences.
> 
> The consequences:
[...]
> * geom_event thread started consuming 100% of CPU in g_wither_washer()

This sounds familiar as well:
http://www.freebsd.org/cgi/query-pr.cgi?pr=171865

Fabian
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