2017-02-05 Problem finaly Found!

The main problem in identifying the cause of the hypervisor issue, was that it was not reproduceable at all. Most of the times the crash happened after several weeks of usage. Now we could find a setup which could reproduce the freeze within 1 hour. The idea was that a so called race-condition happened somewhere in the Hypervisor kernel. Race-conditions create random like crashes, like in our case with a timescale of a few weeks. The key is to create enough load, so that the race-condition would happen faster. We have tried several things to push the race-condition, but so far we had no success until now. By using the fio - I/O generating tool, we where finaly able to reprodruce the crash within 1 hour, this helped in testing different Kernels and settings out. 

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