The devices don't appear to have the same serial or even the same product name, I'm unsure why they're be considered as multipathed even with the apparent same scsi_id as you've discovered.
What does multipath -ll output on this system? Also, could you please run the following commands: for d in /dev/sda /dev/sdb; do echo "page 0x80: $d:'$(sudo /lib/udev/scsi_id --whitelisted --page=0x80 --device=$d)'"; done for d in /dev/sda /dev/sdb; do echo "page 0x83: $d:'$(sudo /lib/udev/scsi_id --whitelisted --page=0x83 --device=$d)'"; done for d in /dev/sda /dev/sdb; do echo "page pre: $d:'$(sudo /lib/udev/scsi_id --whitelisted --page=pre-spc3-83 --device=$d)'"; done In case we're dealing here with non-standard devices, I'd like to whether there is an alternative method we can use that would get better results. We've seen here that page 0x83 was used, but we should find out whether 0x80 is available, or if this also needs kernel/driver work. ** Changed in: multipath-tools (Ubuntu) Status: Triaged => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1463046 Title: installation of multipath-tools-boot can break boot To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/1463046/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs