file corruption on tape reload

[J. Hart]

     I have been having difficulty making a good tape backup recently.  I use
the following command to back up a directory :

     tar cvM -f /dev/st0 2>&1 aminet | tee log

I reload that into a seperate directory using the following command :

     tar xvM -f /dev/st0 2>&1 | tee log

     When I compare the original with the reloaded backup, I find that one of
the files in the reloaded version is corrupted.  It turns out that a contiguous
block of exactly 4096 bytes is corrupt.  If I reload the same backup tapes
again, the corruption shows up at a different point in a different file, but the
corruption still involves a block of exactly 4096 bytes.

     I had previously used this same tape drive on an older machine running
Slackware 4 and a stock kernel until very recently, and it worked perfectly
there.  I am using the exact same model under RedHat 6.2 and the 2.2.16 kernel
on another machine, and that works perfectly.  I have tried changing tapes and
cleaning the drive tape path, with no effect on the problem.  I have also tried
upgrading the kernel to the most recent version available at the time (then
2.4.16) to no avail.  I then tried rebuilding the kernel to use "aic7xxx_old"
support, also with no change in the problem.  There is no indication of any
error in any of the logs I have checked (dmesg, /var/log/messages).

Does anyone have any idea on what I should be looking at here ?

My setup is as follows :

CPU                : 900mhz Athlon
motherboard        : ASYS-A7V
linux distribution : Slackware 8
kernel             : 2.4.16
scsi controller    : AHA-2940AU
scsi drivers tried : aic7xxx
                   : aic7xxx_old (after kernel rebuild)
hard disk          : ATA100 IBM-DTLA-307045 45gb
tar version        : tar (GNU tar) 1.13.25
tape drive:
     Vendor: WangDAT  Model: Model 3400DX     Rev: 5.0d
     Type:   Sequential-Access                ANSI SCSI revision: 02


Regards,

     J. Hart

To Unsubscribe: send mail to majordomo at FreeBSD.org
with "unsubscribe aic7xxx" in the body of the message