DLT Tape Read errors on aac0

[Christian Gründemann]

Hi,

I am using an Adaptec SCSI RAID 2120S Card with 5 SCSI
Seagate drives as a RAID-5 without any probelms for almost two years now.

Last week I attached to the aac0 controller a Tandberg DLT Drive
QUANTUM DLT VS160 2500 Removable Sequential Access SCSI-2 device
for large backup purposes.

We decided to use dump/restore for our backup strategy but 
unfortunately  we can
only make backups and no restores. E.g dumping a filesystem works great:

root at hercules ~ dump -0aLf /dev/sa0 /var
  DUMP: Date of this level 0 dump: Tue Dec 20 15:44:05 2005
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping snapshot of /dev/aacd0s1f (/var) to /dev/sa0
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 63220 tape blocks.
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: DUMP: 64341 tape blocks on 1 volume
  DUMP: finished in 15 seconds, throughput 4289 KBytes/sec
  DUMP: Closing /dev/sa0
  DUMP: DUMP IS DONE
root at hercules ~

I guess the backup has been successfully finished.

But when I try a access the backup ether via the  interactive console or
by trying  to extract the data directly  I get the follwing errors in 
/var/log/messages

root at hercules /var restore -i -f /dev/sa0
tape read error: Input/output error

Dec 20 15:49:22 hercules kernel: (sa0:aacp0:0:5:0): READ(06). CDB: 8 0 0 
80 0 0
Dec 20 15:49:22 hercules kernel: (sa0:aacp0:0:5:0): NO SENSE ILI (length 
mismatch): 22528 csi:e0,40,0,20 asc:0,0
Dec 20 15:49:22 hercules kernel: (sa0:aacp0:0:5:0): No additional sense 
information

Sometimes I often get some Timeouts (only using restore).
Dec 19 11:34:27 hercules kernel: aac0: COMMAND 0xc1fdf750 TIMEOUT AFTER 
51 SECONDS

Kernel config:
-------------------------
# SCSI peripherals
device          scbus           # SCSI bus (required for SCSI)
device          ch              # SCSI media changers
device          da              # Direct Access (disks)
device          sa              # Sequential Access (tape etc)
device          cd              # CD
device          pass            # Passthrough device (direct SCSI access)
device          ses             # SCSI Environmental Services (and SAF-TE)
# RAID controllers
device          aac             # Adaptec FSA RAID
device          aacp            # SCSI passthrough for aac (requires CAM)
-------------------------

dmesg (cutted):
------------------
hercules kernel: CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2399.33-MHz 
686-class CPU)
hercules kernel: FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
hercules kernel: cpu0 (BSP): APIC ID:  0
hercules kernel: cpu1 (AP): APIC ID:  1
hercules kernel: cpu2 (AP): APIC ID:  6
hercules kernel: cpu3 (AP): APIC ID:  7

aac0: <Adaptec SCSI RAID 2120S> mem 0xd0000000-0xd3ffffff irq 52 at 
device 2.0 on pci4
aac0: [FAST]
aac0: Unknown processor 100MHz, 48MB cache memory, optional battery not 
installed
aac0: Kernel 4.1-0, Build 7244, S/N bd10c2
aac0: Supported 
Options=11d7e<CLUSTERS,WCACHE,DATA64,HOSTTIME,RAID50,WINDOW4GB,SOFTERR,SGMAP64,ALARM,NONDASD>
aacp0: <SCSI Passthrough Bus> on aac0

acpi_cpu: throttling enabled, 8 steps (100% to 12.5%), currently 100.0%
(probe5:aacp0:0:5:0): TEST UNIT READY. CDB: 0 0 0 0 0 0
(probe5:aacp0:0:5:0): NOT READY csi:e0,40,0,1c asc:4,1
(probe5:aacp0:0:5:0): Logical unit is in process of becoming ready
sa0 at aacp0 bus 0 target 5 lun 0
sa0: <QUANTUM DLT VS160 2500> Removable Sequential Access SCSI-2 device
sa0: 160.000MB/s transfers (80.000MHz, offset 96, 16bit)
----------------------

Does anybody maybe have an idea why I can use dump but not restore ?
This doesn't make sense to me.

And I should mention that "tar" works great! I can  write and read from 
the tape, even with filemarks.

Thanks for your help!
Christian