problem with 4T volume under FreeBSD

Hello,

I have weird problem with volume over 2TB in size.

GELI was reporting data corruption:
GEOM_ELI: da6.eli: 58304 bytes corrupted at offset 2624722698240.

So, advised by pjd, using gpt I created da6p2 starting at that offset:
       start        size  index  contents
          34  5126411486      1  GPT part - FreeBSD UFS/UFS2
  5126411520  3662648031      2  GPT part - FreeBSD UFS/UFS2

And did simple test of:
  # dd if=/dev/random of=/tmp/test.rand bs=64k count=1
  # dd if=/tmp/test.rand of=/dev/da6p2 bs=64k count=1
  # dd if=/dev/da6p2 bs=64k count=1 | md5
  # md5 /tmp/test.rand
Those sums were the same.

However this:
  # dd if=/dev/random of=/tmp/test.rand bs=72k count=1
  # dd if=/tmp/test.rand of=/dev/da6p2 bs=72k count=1
  # dd if=/dev/da6p2 bs=72k count=1 | md5
  # md5 /tmp/test.rand
yielded different results.

It looks like corruption during write.

FreeBSD 6.2-PRE (cvsuped yesterday, aic7xxx.c,v 1.109), 
ahc0: <Adaptec 29160 Ultra160 SCSI adapter> port 0x2000-0x20ff 
      mem 0xfc302000-0xfc302fff irq 20 at device 8.0 on pci1
aic7892: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs
da6 at ahc0 bus 0 target 13 lun 3
da6: <SB-3160S Volume Set # 03 R001> Fixed Direct Access SCSI-3 device 
da6: 160.000MB/s transfers (80.000MHz, offset 62, 16bit), Tagged Queueing Enabled
da6: 4291533MB (8789059584 512 byte sectors: 255H 63S/T 547093C)

That da6 is volume created on Simbolo Proware (RAID6 from eight 750GB ATA disks),
oferred out via SCSI interface, using 64 LBA interface.

I had similar problem 2 years ago, but I worked around it by not using volumes
over 2TB in size (and they worked fine since then) and above would probably be
"fixed" the same way, but I'd rather have 4T volumes...

This of course may be a problem in SB-3160S, but it also may be a problem
of Adaptec controller. I will try to find another controller (which are
proven to work with >2TB, btw?) to verify that further.

Any help or further directions appreciated.

p.

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