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 Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1451277 Title: Extremely high IOWait and processes hungs after utopic->vivid upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1451277/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
