Xenserver tapdisk experienced an error

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┬áServer_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.



  • Hey,

    I saw your original comment at zenserver.org, and then came over here to give you a huge “Thank you!”

    Started a new round of OS testing and no *new* VMs would boot – never had this issue with 6.2, and started freaking out because we were rapidly approaching critical mass where we were going to try to revert 6.5 back to 6.2 (IOW – restore a 3 week old backup).

    Simply ejecting the storage optical drive prior to booting any VM, existing or new, fixed the issue.

    Thanks again ­čÖé

  • Andre Cavalcanti

    Try this:

    xe vm-cd-eject –multiple

  • Excuseme if I reopened this case, but my problem is relationated with this. I have a problem with a new xenserver 6.5. When I create new vm and I intent install some “os” from the dvd/cd drive, I receive “tapdisk experienced an error”. In the log the error is different to the showed here:

    udev: EXCEPTION SR.SROSError …tapdisk experienced an error… opterr=No medium found

    I did all what is mentioned in this thread but the problem persists. Can you help me?

  • This error was for when you made a new VM but connected existing disks to it not a new VM. When happens when you try and boot he VM from a ISO?

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