Mounting /usr during boot on RPI2

[bob prohaska]

Got an RPI2 system up and running for a few weeks now. For the
most part it's astoundingly robust, but there are a few small
mysteries.

If /etc/fstab is edited with the line
/dev/da0p3      /usr            ufs rw,noatime,late,failok              1 2
boot fails and drops into single user, saying device not found,
as if /dev isn't fully populated yet. In single user, a manual
fsck -y cleans up the problem and exit starts multiuser.

Adding a mount command in /etc/rc.conf works but there are
several attempts, with repeated "device busy" and "device
already in use" reports. Eventually /usr mounts from the
usb hard disk and everything works very well.

Another oddity is that adding fsck -Cy before the mount
command always seems to result in a full fsck, even when
the machine went through a clean reboot.

Adding swap in /etc/rc.conf likewise works, but with
repeated "device already in use" reports during boot.

I've tried adding 
SCSI_DELAY=20000 to the kernel config file in hopes it
might let the usb device catch up, but the variable seems
to have no effect-

It looks as if the boot process runs too fast for the usb
daemons to keep up. Is there some way to slow it down?

For now, the solution seems to be in leaving /etc/fstab
strictly alone and mount /usr in /etc/rc.conf without
invoking fsck -Cy. If the /usr partition is dirty, it
simply must be fsck'd and mounted by hand. 

Altogether the machine works astonishingly well, despite
the little niggles.

With my compliments and thanks to everybody involved,

bob prohaska