[pve-devel] Default cache mode for VM hard drives

Stanislav German-Evtushenko ginermail at gmail.com
Thu May 28 19:12:26 CEST 2015


> Your test code was a really interesting example, and lead to
> really unexpected results (at least for me). But as Eneko already
> mentioned, nobody would write such code. It is simply not thread save,
> and I think qemu does it correctly.

I have written that code only because nobody wanted to test real-life
test cases I had provided (VM with low memory and Windows 7 inside).
However now I think it is going to be even easier to reproduce in a
VM. My guess if you install a VM with virtual drive on DRBD or MD RAID
and cache=none, create ext3 or ext4 partition inside this VM and run
my code inside then you will get inconsistence. May be you need to run
it not once but 10-20 times but finally it should happen.

Stanislav


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