[vbox-dev] disk I/O crashes of FreeBSD 9.1-P7 guest on Mac OS X 10.8.5 host

[Klaus Espenlaub]

Hi Axel,

On 22.09.2013 13:38, Axel Rau wrote:
> Hi,
>
> This VM exists 6 month now and worked perfect.
> Recently I upgraded the host from 10.8.4 to 10.8.5.
> Today, I started the VM after a break of 2 month after upgrading VBox to 4.2.18r88780.
> After that, I updated freebsd 9.1 to 9.1-P7 using freebsd-update.
> Everything worked perfect so far.
> Then I did a portsnap fetch and a portsnap update, which froze the VM immediately (lots of directories/file had to be removed).
> After a few seconds the VM started rebooting but was unable to find the root disk (a SATA drive), until I powered down and restarted.
> This was reproducible.
> After that I switched the disks to a IDE controller: Same crash on portsnap update. Only difference: It completed its reboot.

Sounds like the host is not able to handle the I/O within the timeout 
imposed by the guest OS. OSX is known for bad I/O performance, it is 
easily overloaded, resulting in unbearable response time for I/O 
requests (we've seen a 64K write request taking 3 minutes, and there are 
probably worse situations). There is very little VirtualBox can do about 
this.

> Nothing interesting in the logs.

Which logs? Host (normal OSX logging and VBox.log) and guest logs?

> This is a 6-core Xeon, 2 cores dedicated to the VM.

Sounds unlikely that you have dedicated cores for the VM... guess you 
simply set the VCPU count to 2.

> Questions: Has this combination of host/guest OS versions been tested?

Probably not - there is a near infinite number of combinations, and you 
use a quite unusual one.

> What can I do to further help finding the cause?

Clarifying which log looks normal would provide a starting point.

Klaus

>
> Thanks, Axel
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