Interesting. I had a guy at a previous job who was using a bootable Linux thumb drive (not live, drive and ram were the primary storage) I had made with some preset tools. He kept complaining the file system was corrupting- turns out when he was done he would take out the thumb drive (his idea of a shut down). I've also accidentally pulled a thumb drive running Linux out before- usually panics in about 30 seconds, and plugging it in quickly when remembering it's the system drive doesn't help ;-) -- Jeremy MountainJohnson Jeremy.MountainJohnson at gmail.com On Thu, Jan 31, 2013 at 2:00 PM, Erik Anderson <erikerik at gmail.com> wrote: > > On Thu, Jan 31, 2013 at 9:37 AM, Munir Nassar <tclug at beitsahour.net> wrote: >> >> If linux crashed hard, it may not have had the ability to write to >> disk. sometimes it is preceeded by oopses or non-fatal panics, but in >> my experience not often enough. > > > This reminded me of something interesting I discovered accidentally a couple years ago. My employer at that time had a fibre channel fabric, connecting all of our headless servers to their storage. > > I was performing some maintenance on the switch fabric, the nature of which I can't remember at the moment, but regardless, it required me to disconnect a couple fiber patch cables. I pulled out one of the cables and then got distracted for a couple minutes by something else. During that time I started getting pages about a system being inaccessible. I started looking into the situation and quickly discovered that instead of disconnecting the cable I had intended to, I accidentally pulled the cable connecting this server to our FC network, effectively pulling its storage subsystem out from under its feet. > > I re-patched that cable, then pulled up this server's console, fully expecting to see a kernel panic. Instead of seeing that, I saw what appeared to be a completely functional system. Not believing what I was seeing, I checked the system's uptime and sure enough, it indeed had not rebooted, but rather just picked up right where it left off before. > > Armed with this information, I started playing around with a test system to see how long the kernel would stay alive with *no* storage connected, and was able to stretch things out well past the 15 minute mark with no ill effects. > > This all was a revelation to me, as I had always assumed that, absent a working root partition, the system would immediately crash. I now know that's not the case. > > Now, in this situation, the disks were connected via fibre, so there were no electrical/grounding ramifications to disconnecting while in use. I certainly would not advocate trying this on non-hotplug, electrically-connected hardware, as I'm sure you'd release the magic smoke from *some* component. :) > > -Erik > > > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > tclug-list at mn-linux.org > http://mailman.mn-linux.org/mailman/listinfo/tclug-list >