Hi After upgrading a few of our Xenservers to 6.5 i moved a few hard drives from some troublesome servers. I found that after they were remounted i would get a error saying “tapdisk experienced an error” after a bit of digging around in the logs i found Server_helpers.exec exception_handler: Got exception SR_BACKEND_FAILURE_449: [ ; tapdisk experienced an error [opterr=No medium found]; ]
I checked the VDI’s and i could access them via a live CD i mount in the VM. After i rebooted and ejected the CD i found the VM would now boot. I try the same thing on the 2 other servers that would boot and now they are all happy. It seems that when you create a VM for the first time it needs to boot from the CD drive at least once to fix this error.
Hopefully this saves some one some time i spent a few hours on this and couldn’t find any real useful info on it.