If it indeed is the triggering commit. Comparing two memory map file for
the kernel with and without the commit, could show off its a compilation
issue.
On Apr 14, 2016 09:21, "Frederik Bosch" <email address hidden> wrote:

> For the information, this is the commit
>
> https://github.com/torvalds/linux/commit/c01fac1c77a00227f706a1654317023e3f4ac7f0
> .
> It would indeed make no sense at all when this would cause the thing.
> How would the backup procedure even touch those lines of code?
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1470250
>
> Title:
>   [Hyper-V] Ubuntu 14.04.2 LTS Generation 2 SCSI Errors on VSS Based
>   Backups
>
> Status in linux package in Ubuntu:
>   In Progress
> Status in linux source package in Trusty:
>   In Progress
> Status in linux source package in Vivid:
>   In Progress
> Status in linux source package in Wily:
>   In Progress
> Status in linux source package in Xenial:
>   In Progress
>
> Bug description:
>   Customers have reported running various versions of Ubuntu 14.04.2 LTS
>   on Generation 2 Hyper-V Hosts.    On a random Basis, the file system
>   will be mounted Read-Only due to a "disk error" (which really isn't
>   the case here).    As a result, they must reboot the Ubuntu guest to
>   get the file system to mount RW again.
>
>   The Error seen are the following:
>   Apr 30 00:02:01 balticnetworkstraining kernel: [640153.968142] storvsc:
> Sense Key : Unit Attention [current]
>   Apr 30 00:02:01 balticnetworkstraining kernel: [640153.968145] storvsc:
> Add. Sense: Changed operating definition
>   Apr 30 00:02:01 balticnetworkstraining kernel: [640153.968161] sd
> 0:0:0:0: Warning! Received an indication that the operating parameters on
> this target have changed. The Linux SCSI layer does not automatically
> adjust these parameters.
>   Apr 30 01:23:26 balticnetworkstraining kernel: [645039.584164]
> hv_storvsc vmbus_0_4: cmd 0x2a scsi status 0x2 srb status 0x82
>   Apr 30 01:23:26 balticnetworkstraining kernel: [645039.584178]
> hv_storvsc vmbus_0_4: stor pkt ffff88006eb6c700 autosense data valid - len
> 18
>   Apr 30 01:23:26 balticnetworkstraining kernel: [645039.584180] storvsc:
> Sense Key : Unit Attention [current]
>   Apr 30 01:23:26 balticnetworkstraining kernel: [645039.584183] storvsc:
> Add. Sense: Changed operating definition
>   Apr 30 01:23:26 balticnetworkstraining kernel: [645039.584198] sd
> 0:0:0:0: Warning! Received an indication that the operating parameters on
> this target have changed.  The Linux SCSI layer does not automatically
> adjust these parameters.
>
>   This relates to the VSS "Windows Server Backup" process that kicks off
> at midnight on the host and finishes an hour and half later.
>   Yes, we do have hv_vss_daemon and hv_kvp_daemon running for the correct
> kernel version we have.   We're currently running kernel version
> 3.13.0-49-generic #83 on one system and 3.16.0-34-generic #37 on the other.
> -- We see the same errors on both.
>   As a result, we've been hesitant to drop any more ubuntu guests on our
> 2012R2 hyper-v system because of this.   We can stop the backup process and
> all is good, but we need nightly backups to image all of our VM's.   All
> the windows guests have no issues of course.   We also have some CentOS
> based guests running without issues from what we've seen.
>
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>