Odd behavior with virtualbox-ose-4.3.38

[Jan Mikkelsen]

Hi,

> On 23 Aug 2016, at 02:25, Kevin Oberman <rkoberman at gmail.com> wrote:
> 
> On Mon, Aug 22, 2016 at 1:50 AM, Jan Mikkelsen <janm at transactionware.com <mailto:janm at transactionware.com>> wrote:
> Do you have aio loaded or compiled into your kernel? If so, does it keep happening without aio?
> [ … ]
> Thanks for the suggestion, but, no. This is on my trusty Lenovo T520 laptop and no aio to be found. My configuration is just:
> include           GENERIC
> ident             GENERIC_BSD4
> 
> nooptions         SCHED_ULE               # ULE scheduler
> options           SCHED_4BSD              # 4BSD scheduler
> 
> I still can't be sure if the problem was triggered by the move to VB 5 or t FreeBSD-11 (or a combination of both).

Yes, the problem could be in many places. However, if you’ve gone to FreeBSD 11, you have more aio than you think.  From UPDATING:
20160301:
	The AIO subsystem is now a standard part of the kernel.  The
	VFS_AIO kernel option and aio.ko kernel module have been removed.
	Due to stability concerns, asynchronous I/O requests are only
	permitted on sockets and raw disks by default.  To enable
	asynchronous I/O requests on all file types, set the
	vfs.aio.enable_unsafe sysctl to a non-zero value.
Are you running the VM against a raw disk device? You can check the VBox.log output — If you are not using aio, you should see an entry like this:

AIO: Async I/O manager not supported (rc=VERR_NOT_SUPPORTED). Falling back to simple manager

If you are using AIO, you will should see entries like:

AIOMgr: Default manager type is "Async"
AIOMgr: Default file backend is “NonBuffered"


AIO issues were not a big issue for a long time but some recent updates to 4.3.something (or other environmental issues, possibly load) led me to turn aio off on a bunch of 10.x machines running a significant number of VMs (~25). I’m have been curious about whether the aio change would cause problems with an upgrade to 11.

Regards,

Jan.