I found a bug in recent Finnix: I think I observe kernel panic when sd
storage is removed during write.
It was a few months ago, when I first observed a problem. I was using
SystemRescueCd then, playing with more than one ATA-ATA bridge in a
chain, and the system 'froze solid' when I attempted to write to HDD.
I did not investigate further, because I thought it was a problem
caused by my non-sane hardware setup.
http://forum.thinkpads.com/viewtopic.php?f=2&t=112081&p=727826#p727826
Since then, I switched to Finnix as my go-to LiveCD. A few days ago, I
observed Finnix hang/freeze/lockup when cloning discs. Destination
drive was attached through a notoriously unreliable JM20337 bridge, to
Intel xHCI host. I thought, maybe that is just a bug in xHCI code
which was not combed-out yet. So I tried a different PC with EHCI and
OHCI hosts: the same freeze happened when I violently jiggled the
cables. I began to realize: this problem is not specific to Finnix nor
SystemRescueCd, and not specific to ATA nor USB.
I guess this bug is either in kernel, or something else which both
SysRescCd and Finnix have in common, perhaps related to RAMdisk,
perhaps a particular cache setting. I do not know whether this bug is
specific to sd, or affects also other types of discs.
This is easy to reproduce. Find any spare USB Stick, or ATA PC Card,
or other storage device to be overwritten. Start Finnix 109 or Finnix
110. Run either:
cat < /dev/zero > /dev/sd#
pv < /dev/zero > /dev/sd#
Then pull-out Stick while write pending.
Assuming it is a kernel problem: it is present in SystemRescueCd 3.7.1
alternative kernel 3.9.10. It is not present in Finnix 108 kernel 3.8.
Finnix 108 is the most recent release which does not exhibit this
problem. I think it qualifies as a bug, at least in user experience.
A common use case is data rescue, often with flakey or failing
hardware. Finnix should survive drive failure, especially USB (very
many ATA to USB bridges have problems).
I am not knowledgable enough to dig deeper. I doubt I can help
troubleshoot any further.
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