After tons of testing, I strongly suspect that the issue was with a failing SATA cable, passing next to the IDE cable of the ZIP disk. Whenever detaching the ZIP, I was probably bending the SATA cable in such a way that made it work more reliably. Now the cable has failed altogether and, after replacement, the high IOWAIT seems to be gone, even with the ZIP disk attached.
Sorry for the noise -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1451277 Title: Extremely high IOWait and processes hungs after utopic->vivid upgrade Status in linux package in Ubuntu: Incomplete Bug description: On Kubuntu, 64 bit AMD Phenom2 machine with 4 cores, and old (Geoforge 7025) Nvidia graphics. Using LVM. Machine also has a 2 disk software raid (mirroring). The machine was working fine before the upgrade, now it is almost impossible to use it... I see Wait in Top always above 60%; in dmesg after a few minutes that the machine is up even if the machine does nothing. I see hung processes (typically vgs, but occasionally also others). LVM related commands (e.g. lvdisplay) almost always hung at the terminal. I also see in ps some kernel workers almost constantly stuck in D state. Also, the machine takes ages to shutdown. Issue remains there also if I disable X (switch off the X login manager, sddm) and check at the console. Sorry I cannot provide details with apport, but the machine has been switched off and I will not be able to take it up again before a few days from now. The symptom I am observing may also be a sign of failing hardware, so please leave the bug as unconfirmed until I make some more tests or someone provide details on similar issues. In the meantime I would like to see if others are experiencing a similar serious issue. Is there anything specific that has changed between utopic and vivid, I should look into? To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1451277/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
