From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
owner@vger.kernel.org] On Behalf Of Roland Dreier
Sent: January 18, 2012 1:46 PM
To: Ric Wheeler
Cc: linux-fsdevel@vger.kernel.org; linux-scsi@vger.kernel.org
Subject: Re: [LSF/MM TOPIC] linux servers as a storage server - what's
missing?

quoted

Why would you crash is you have device mapper multipath configured

to

handle

quoted

path fail over? We have tons of enterprise customers that use

that...

cf http://www.spinics.net/lists/linux-scsi/msg56254.html

Basically hot unplug of an sdX can oops on any recent kernel, no
matter what dm stuff you have on top.

Depends on the use-case. In the particular (SAN)use-case that I'm
talking about, 
you shouldn't unplug live sdX which is still mapped on the target(array)
side.
I've attempted to fix it somewhere and it works. If you need more info
about eh and initiator fixes, email me offline.

When would this case arise? :
a) you unknowingly unmap *hot* LUNs from target(array) while managing
the array.

End result - reset storm on front-end. You just need a smarter way to
isolate/localize this
front-end storm.


Chetan Loke