Areca Weirdness

[Lawrence Farr]

I've got an Areca 12 port card running a 6Tb array which is divided
into 2.1Tb chunks at the moment, as it was doing the same with a
single 6Tb partition.

ad0: 58644MB <IC35L060AVER07 0 ER6OA44A> at ata0-master UDMA100
da0 at arcmsr0 bus 0 target 0 lun 0
da0: <Areca Arc1 R001> Fixed Direct Access SCSI-3 device
da0: 166.666MB/s transfers (83.333MHz, offset 32, 16bit), Tagged Queueing
Enabled
da0: 2224922MB (4556640256 512 byte sectors: 255H 63S/T 283637C)

If I newfs it, and copy data to it, I have no problem initially.
If I then try and copy the data on the disk already to a new
folder, the machine reboots (it's a remote host with no serial
attached currently). When it comes back to life, it mounts, and
shows as:

/dev/da0       2.1T    343G    1.6T    18%    /usr/home/areca1

But is completely empty. Unmounting it and trying to fsck it
errors, as does mounting it by hand.

[root at nas-2 /home]# fsck -y /dev/da0
** /dev/da0
Cannot find file system superblock
ioctl (GCINFO): Inappropriate ioctl for device
fsck_ufs: /dev/da0: can't read disk label
[root at nas-2 /home]# mount /dev/da0
mount: /dev/da0 on /usr/home/areca1: incorrect super block

Are there any known issues with the driver on AMD64? I had
major issues with it on Linux/386 with large memory support
(it would behave equally strangely) that went away when I
took large memory support out, maybe there are some non 64
bit safe parts common to both?