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Date: Sat, 8 Feb 2014 14:01:24 -0600
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Subject: Re: Report of my virtual network lab migrated from virtualbox to bhyve
From: Adam Vande More <amvandemore@gmail.com>
To: Aryeh Friedman <aryeh.friedman@gmail.com>
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On Sat, Feb 8, 2014 at 6:51 AM, Aryeh Friedman <aryeh.friedman@gmail.com>wrote:
>
> bhyve blindly read/writes into the middle of the file without consulting
> the filesystem and thus bypassing any things like sparse fill in.... namely
> all you gain is a few seconds of startup time (matter of fact I think
> truncate might use sparse allocation [i.e. attempting to read into the
> middle with guest OS control will result in potentially seeing host data])
>

If this is true then there is a *critical* security issue.

Using sparse files isn't to gain performance, it's to conserve disk space.
 Using md devices backed by sparse images would accomplish this.  If the
sparsify app works on FreeBSD, then there should be no problem using those
type of volumes.

-- 
Adam