SCSI tape errors.

William M. Perkins (bill@grnwood.grnwood.richmond.us.net)
Thu, 2 May 1996 16:52:46 -0400 (EDT)

About once a week I backup the more important filesystems on my Linux
system to a Conner ST150S2 (QIC150) tape drive. I backup about 700 MB
of system data from three filesystems of 200 to 250 MB each to three
seperate tapes. One filesystem per tape. I use GNU tar version 1.11.8
most of the time to do these backups, but I have also used afio and
cpio. The problem becomes visible when I compare the files on tape
with their originals on disks. The following compare (cmp) errors are
examples of the errors I get:

> [root@grnwood:ttyp5] /trash
> $ cmp -l usr/bin/gtbl /usr/bin/gtbl
> 65665 120 340
> 65666 40 153
> 65667 40 0
> 65668 0 10
> [root@grnwood:ttyp5] /trash
> $ cmp -l usr/man/man1/geqn.1 /usr/man/man1/geqn.1
> 12961 302 160
> 12962 360 141
> 12963 260 143
> 12964 242 151
> [root@grnwood:ttyp5] /trash
> $ cmp -l bill/audio.wav /home/bill/audio.wav
> 115777 40 76
> 115778 40 0
> 115779 40 125
> 115780 40 376
> [root@grnwood:ttyp5] /trash
> $ cmp -l bill/rocky-gorge-cloudy.bmp /home/bill/rocky-gorge-cloudy.bmp
> 1766117 120 200
> 1766118 40 224
> 1766119 40 112
> 1766120 0 214
> [root@grnwood:ttyp5] /trash
> $

I receive, on average, about four to eight of these types of errors
for each filesystem that is dumped. These errors occur when reading the
tape as well as when writing to tape. The read errors are seen by doing
a second verify of the file data on tape with the disk data. The read
errors do not repeat on the second verify run while the write errors
will do so everytime.

For your information my hardware configuration includes the following:
- 486-PSD-IO motherboard with builtin NCR 53c810 and IDE controller
- 486/DX2 66 MHz CPU
- 32 MB of memory (4 - 4x36-60ns)
- SoundBlaster 16 sound card
- 3c503 Ethernet card (thinnet)
- Paradise S3 864 PCI graphic card (2 MB)
- I/O card with 2 - 16550A serial ports
- Acer 56L 15" monitor
- Cardinal 28.8Kb modem
SCSI devices (IDE is disabled) (5 MHz Sync with disconnect enabled)
- CONNER Model: CFP1060S 1.05GB Rev: 213C
- FUJITSU Model: M2684S-512 Rev: 2026
- QUANTUM Model: PD210S Rev: 527
- TOSHIBA Model: CD-ROM XM-3401TA Rev: 2873
- CIPHER Model: ST150S2 (QIC150) Rev: G76M
Short list of software used:
- RedHat 2.1 Linux Nov 1995 distribution (ELF with some a.out)
- kernel 1.3.97
- gcc 2.7.0
- named 5.9.3
- inn 1.4unoff3
- ppp 2.2.0e
- diald 0.11

Anybody have any ideas? The tape drive works just fine on my
Amiga 2500 system, so I do not think it is the problem.

Bill

-- 
William M. Perkins                       Internet - wperkins@us.net
The Greenwood                               or    - bill@cais.com
Commodore is dead.  Long lives the Amiga!  (AmigaOS/Linux/NetBSD)