I posted about this before with the subject trm0: parity error in 2.0 
after reboot.

I have 2 scsi drives that I plan to combine with ccd.  These drives are 
ibm ultrastar 18xp's , they're 80pin, and I'm using 2 80->50pin 
converters to use with with my
Tekram DC395, I had no problems with in 1.6, but with 2.0 I find it 
works OK on initial power up, but gives me generic HBA error, and 
"trm0: parity error"  on subsequent boots.
I now have both drives installed  (I was waiting on a railkit --they're 
too tall to fit in my 3-1/2in bays. ), and started to playing with 
jumper settings hoping maybe I could stumble on something that worked.  
Besides finding combo's where it wouldn't work at all
in 2.0 (instead of just 2nd boot ) I noticed some differences in dmesg 
output, less
drive info on first boot, on 2nd boot more info, "sync (50.00ns offset 
15), 16-bit (40.000MB/s) transfers"   I don't know that much about 
scsi, some explaination about
what is the sync line means might help -- I'd like to be able to jumper 
my way around this and there are 2 jumpers related to sync, SP sync and 
Dis Ti Sy.
Also, can 50 pin do 16bit transfer?


Working:
%dmesg | grep trm0
%dmesg | grep 'trm0\|sd[12]'
trm0 at pci0 dev 11 function 0: Tekram DC395U, DC315/U (TRM-S1040) 
Fast20 Ultra SCSI Adapter
trm0: interrupting at irq 5
scsibus0 at trm0: 8 targets, 8 luns per target
sd1 at scsibus0 target 0 lun 0: <IBM, DXHS, 0430> disk fixed
sd1(trm0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
sd1: drive offline
sd2 at scsibus0 target 1 lun 0: <IBM, DXHS, 0430> disk fixed
sd2(trm0:0:1:0):  Check Condition on CDB: 0x00 00 00 00 00 00
sd2: drive offline
sd1(trm0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
sd2(trm0:0:1:0):  Check Condition on CDB: 0x00 00 00 00 00 00


Not Working:
%dmesg | grep 'trm0\|sd[12]'
trm0 at pci0 dev 11 function 0: Tekram DC395U, DC315/U (TRM-S1040) 
Fast20 Ultra SCSI Adapter
trm0: interrupting at irq 5
scsibus0 at trm0: 8 targets, 8 luns per target
sd1 at scsibus0 target 0 lun 0: <IBM, DXHS18Y, 0430> disk fixed
sd1: 17366 MB, 8154 cyl, 20 head, 218 sec, 512 bytes/sect x 35566480 
sectors
sd1: sync (50.00ns offset 15), 16-bit (40.000MB/s) transfers
sd2 at scsibus0 target 1 lun 0: <IBM, DXHS18Y, 0430> disk fixed
sd2: 17366 MB, 8154 cyl, 20 head, 218 sec, 512 bytes/sect x 35566480 
sectors
sd2: sync (50.00ns offset 15), 16-bit (40.000MB/s) transfers
trm0: parity error
sd1(trm0:0:0:0): generic HBA error
trm0: parity error
sd1(trm0:0:0:0): generic HBA error
trm0: parity error
sd2(trm0:0:1:0): generic HBA error
trm0: parity error
sd2(trm0:0:1:0): generic HBA error
trm0: parity error
sd1(trm0:0:0:0): generic HBA error
trm0: parity error
sd1(trm0:0:0:0): generic HBA error
trm0: parity error
sd2(trm0:0:1:0): generic HBA error
trm0: parity error
sd2(trm0:0:1:0): generic HBA error


Same in 1.6 for comparison:
%dmesg | grep 'trm0\|sd[12]'
trm0 at pci0 dev 11 function 0: Tekram DC395U, DC315/U (TRM-S1040) 
Fast20 Ultra SCSI Adapter
trm0: interrupting at irq 5
scsibus0 at trm0: 8 targets, 8 luns per target
sd1 at scsibus0 target 0 lun 0: <IBM, DXHS18Y, 0430> SCSI3 0/direct 
fixed
sd1: 17366 MB, 8154 cyl, 20 head, 218 sec, 512 bytes/sect x 35566480 
sectors
sd2 at scsibus0 target 1 lun 0: <IBM, DXHS18Y, 0430> SCSI3 0/direct 
fixed
sd2: 17366 MB, 8154 cyl, 20 head, 218 sec, 512 bytes/sect x 35566480 
sectors
sd1: no disk label