From owner-freebsd-hackers@FreeBSD.ORG  Wed Aug  7 11:33:31 2013
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From: Mark Felder <feld@FreeBSD.org>
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Subject: Re: After the FreeBSD VM crash,
 file system in VM got rolled back to some old previous state causing
 data loss
Date: Wed, 07 Aug 2013 06:33:26 -0500
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Virtualbox is very aggressive about caching writes. This is how it
achieves its perceived speed. I wouldn't expect to see this happen on
real hardware. I might have to try this out though and see if I can
reproduce it reliably.