Hacker's ramblings

Earlier I wrote about Hyper-V crashing with BSOD. The entire project was doomed from the beginning. After I managed get the Windows not to crash, all I managed to do is get the Linux installer to hang whenever it attempted to anything major on the hard drive. I configured Hyper-V to provide the hard drive from a .vhdx-file, so I initially suspected that old .vhd-file might help, but no, nothing helped. Any minor operations succeeded, but any sort of normal usage made the Linux to hang.

Symptoms include:

• Console message: "INFO: task jbd2/sda blocked for more than 120 seconds" and instruction to deactivate the warning with:
  echo 0 > /proc/sys/kernel/hung_task_timeout_secs
  Example:
  • http://helpinlinux.com/tag/echo-0-proc-sys-kernel-hung_task_timeout_secs/
• Repeated "Sense Key" -messages in dmesg, example:
  • http://forums.gentoo.org/viewtopic-t-734696-view-next.html?sid=64f39476a9b96703e2a2c998023729b9
• No change in /sys/block/sda/stat:
  • Kernel documentation about block-device stat says that columns 3 and 6 contain the number of sectors read and written.
  • In my hung box, the values don't increase.

I was puzzled about this for a very long time. It took me several hours to bump into Linux-SCSI mailing list's discussion about the issue. There Mr. Olaf Hering describes an issue "storvsc loops with No Sense messages".

Luckily Mr. Hering realized what's going on and made a patch to fix the problem. Unfortunately the fix is not yet pushed into mainstream Linux kernel.

Since I was about to install ArchLinux, I took the trouble of compiling the necessary kernel module of hv_storvsc.ko into following kernel versions:

• 3.8.4, used in installation ISO-image:
  • SHA-1 sum: 74d2a5de73a4c7d963b649eb34b171eba86a268c
• 3.8.6, the version that got installed when I got my install done:
  • SHA-1 sum: 57a4216fc6749085820703d47cd87dcce47b1739
• 3.8.7, the version that it upgraded into when I did a system update:
  • SHA-1 sum: 3f8757ab69c97a6389c7c83a8ef57f16e9caa85d

All of the packages are available for you to download at http://opensource.hqcodeshop.com/ArchLinux/2013.04.01/. Your only trick is to get them replaced into initial RAM-disk -image. I just replaced the original file at /usr/lib/modules and re-ran the mkinitrd-command.