SCSI tape data loss

[Michael L. Squires]

I ran "tapetest.c" under 4.8-STABLE and did not observe any difference
between the version compiled with pthreads and the version compiled
without pthreads.

Without pthreads taptest wrote and read 141,776 blocks on a DLT III (10/20GB)
tape in a DLT4000 drive; with pthreads it wrote and read 142,879 blocks.

Results using 5.1-RELEASE running on another system were similar, i.e., no 
difference between the number of blocks written and read using either pthreads 
or not using pthreads.

4.8-STABLE is running on a Supermicro P6DGH with dual PII/300's, onboard 
Adaptec U2W controller, ADIC VLS DLT changer with DLT4000 tape drive.
5.1-RELEASE is running on a Supermicro P6DGH with dual PIII/850's, onboard
Adaptec U2W controller, single DLT4000 tape drive.

MLS

>From dmesg:
----------------------------------------------------------------------------
FreeBSD 4.8-STABLE #1: Mon Aug  4 21:05:33 EST 2003
    root at newserv.siralan.org:/usr/obj/usr/src/sys/NEWSERV
Timecounter "i8254"  frequency 1193182 Hz
CPU: Pentium II/Pentium II Xeon/Celeron (300.68-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0x634  Stepping = 4
  Features=0x80fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,MMX>
real memory  = 268304384 (262016K bytes)
config> q
avail memory = 255660032 (249668K bytes)

FreeBSD/SMP: Multiprocessor motherboard: 2 CPUs
 cpu0 (BSP): apic id:  0, version: 0x00040011, at 0xfee00000
 cpu1 (AP):  apic id:  1, version: 0x00040011, at 0xfee00000
 io0 (APIC): apic id:  2, version: 0x00170011, at 0xfec00000

ahc0: <Adaptec aic7896/97 Ultra2 SCSI adapter> port 0xe000-0xe0ff mem 0xfebfd000-0xfebfdfff irq 10 at device 14.0 on pci0
aic7896/97: Ultra2 Wide Channel A, SCSI Id=7, 32/253 SCBs
ahc1: <Adaptec aic7896/97 Ultra2 SCSI adapter> port 0xe400-0xe4ff mem 0xfebfe000-0xfebfefff irq 10 at device 14.1 on pci0
aic7896/97: Ultra2 Wide Channel B, SCSI Id=7, 32/253 SCBs

SMP: AP CPU #1 Launched!

sa0 at ahc2 bus 0 target 2 lun 0
sa0: <Quantum DLT4000 CD50> Removable Sequential Access SCSI-2 device 
sa0: 10.000MB/s transfers (10.000MHz, offset 15)
----------------------------------------------------------------------------

Tapetest output:

no pthread:

Write failed.  Last block writen=141776.  stat=0 ERR=Unknown error: 0
End of tape
Total files=1, blocks=141776, bytes = 556318720

with pthread:

rawfill:
Write failed.  Last block written=142879. stat=-1 ERR No space left on device

scan:
Bad status from read -1.  ERR=Input/output error
142879 blocks of 64512 bytes in file 0

Mike Squires