While having a second look at this I can conclude that the messages from device-mapper are due to a device that is not a multipath target, in which case it should be blacklisted in the multipath config file. This will make multipath to not map them, and using this we were able to no longer see the error messages. I was able to verify this on a 15.04 with upstream.
Ignoring local disks from multipath is also detailed here: https://help.ubuntu.com/lts/serverguide/multipath-setting-up-dm- multipath.html Given this and the fact that this didn't pose any issues from the initial report, we can close this issue. -- 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/1511534 Title: [Hyper-V] Fibre Channel multipath error message Status in linux package in Ubuntu: Triaged Status in linux source package in Wily: Triaged Status in linux source package in Xenial: Triaged Bug description: Problem statement: Wily (and probably other previous releases with the updated kernels) return a multipath error for vFC (virtual Fibre Channel). Symptoms: The following messages are in the dmesg log during booting: device-mapper: table: 252:4: multipath: error getting device device-mapper: IOCtl: error adding target to table After logging in, run the command: multipath -ll The multipath command does not return any errors, and no new messages are added to the dmesg log or syslog after running the multipath command. Steps to repro ============ Tested with the released Wily (15.10), kernel 4.2.0-16-generic. 1. Create a Wily VM. 2. Boot and install the multipath-tools package. 3. Shutdown and attach a Virtual Fiber Channel adapter and connect it to a virtual SAN. Note: The host must have a Fiber Channel adapter. Use Hyper-V managers Virtual SAN Manager to create a Virtual Fiber Channel Storage Area Network. 4. Boot the VM. 5. Issue the following command to see any errors were reported during the boot. dmesg | grep -i error You should see the following two error: device-mapper: table: 252:4: multipath: error getting device device-mapper: IOCtl: error adding target to table Otherwise, the vFC disks are usable and show no issues at a use test case. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1511534/+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