bin/59570: tar fails with physical tape drives

[brandon%burn.net@localhost]

>Number:         59570
>Category:       bin
>Synopsis:       tar fails with physical tape drives
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Aug 03 21:20:00 +0000 2025
>Originator:     Brandon Applegate
>Release:        10.1
>Organization:
>Environment:
>Description:
When using tar with a (SCSI) attached tape drive, writing appears to succeed.  However reading fails with "damaged archive" / "skipping header" messages.  I have tried:

- Multiple tape drives.
- Multiple block sizes. (tar -b)
- Using tar to create a tar file - dd'ing this to tape.  dd'ing it back off to a file.
- Using gtar from pkgsrc
- Multiple architectures (amd64, hppa, sparc).

Using the same drive and tape on a Solaris or Linux system behaves correctly (no errors).

I had a thread on netbsd-users here:

https://mail-index.netbsd.org/netbsd-users/2025/07/22/msg032890.html

I tested a few releases going backwards from 10.1 and it seems that 7.2 let me use the tape drive with no errors.

The fact that tar/gtar/dd all have essentially the same failure modes makes me think something is wrong in the st driver nowadays ?

I have multiple drives and machiens and am happy to run any tests requested.


>How-To-Repeat:
Connect known good tape drive, use known good tape.

tar -cpvf /dev/st0 /usr/pkg

tar -xpvf /dev/st0
>Fix: