Subject: Re: Strange tape behavior
To: None <>
From: Ben Harris <>
List: current-users
Date: 10/14/2006 13:36:06
In article <> you write:
>  This message is in MIME format.  The first part should be readable text,
>  while the remaining parts are likely unreadable without MIME-aware tools.
>Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
>Resetting context: the Certance (Quantum) TR-40 tape drive seems to 
>write only 1/2 of the data specified in a write command.
>Attempting to debug this a bit, I've turned on SCSI_DEBUG and 
>SCSIPI_DEBUG.  The result are attached.  Perhaps someone who
>actually knows something about how this stuff works could take
>a quick look and see if there's anything obvious going on?

I don't know much about it, but I have some idea where the confusion is.  
The write command I looked at in there has a length of 0x20.  NetBSD 
seems to be treating the device as having 1024-byte blocks, so that 
would make sense as a number of blocks to write if you're still testing 
with 32K blocks.  If something somewhere thought that blocks were 512 
bytes (which would be the correct value for older Travan formats), it 
would take that as a 16K write, which is what you're seeing.

The questions remain: which block size is correct, and what is getting 
it wrong?

Ben Harris                                                   <>
Portmaster, NetBSD/acorn26               <>