Please help me diagnose this crazy VMWare/FreeBSD 8.x crash

Joe Greco jgreco at
Fri Mar 30 00:27:36 UTC 2012

> > And then there is this one with similar symptoms and a workaround:
> >
> >
> I'm now investigating those loader.conf options. I have my crashy machine
> set to use them on next boot so we'll see if it crashes now that I'm using
> LSI SAS emulated controller. If it still crashes, we'll see what happens 
> after that with those loader.conf options enabled.

Um, if I may, that's something completely different.

VMDirectPath, or PCIe passthru, is making a hardware device on a VMware
host available directly to a guest.  It'll take your LSI controller, in
the example cited, and make it unavailable to VMware ESXi, and present
it instead inside the guest environment.  You do this when you have an
app whose performance would suffer greatly when made to operate through
the indirection that a VM naturally lives in; for example, it is quite
common for FreeNAS users to pass a disk controller through to a VM guest
in order to allow a virtualized FreeNAS instance to directly manage the
physical disks.

In that case, there are some issues with ESXi and interrupt delivery to
the guest VM; virtualization doesn't actually get rid of the possibility
of ESXi problems, since the hypervisor is still ultimately involved.  It
is certainly possible that there's some common issue involving interrupt
delivery somehow, but I wouldn't get my hopes up.

It also doesn't explain the experience here, where one VM basically
crapped out but only after a migration - and then stayed crapped out.
It would be interesting to hear about your datastore, how busy it is,
what technology, whether you're using thin, etc.  I just have this real
strong feeling that it's some sort of corruption with the vmfs3 and thin
provisioned disk format, but it'd be interesting to know if that's 
totally off-track.

... JG
Joe Greco - Network Services - Milwaukee, WI -
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.

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