[193] in linux-scsi channel archive
Re: SCSI Reset Functions.
daemon@ATHENA.MIT.EDU (Kai Makisara)
Mon May 22 06:19:50 1995
Date: Mon, 22 May 1995 12:44:09 +0300 (EET DST)
From: Kai Makisara <makisara@abies.metla.fi>
Reply-To: Kai.Makisara@metla.fi
To: "Leonard N. Zubkoff" <lnz@dandelion.com>
Cc: eric@aib.com, linux-scsi@vger.rutgers.edu, drew@boulder.openware.com
In-Reply-To: <199505220730.AAA32713@dandelion.com>
On Mon, 22 May 1995, Leonard N. Zubkoff wrote:
...
> * Tape drives. I suggest that all access should fail after a reset
> until the user rewinds the tape, or we get a media change. This
> could be tricky, because a UNIT ATTENTION is also used to indicate
> a media change, so it might be difficult to tell whether the
> tape position is no longer lost. Do we want to force the
> user to rewind in all cases? Can we query the device to find
> out if it is at BOT, and if so clear the flag, else command
> fail?
>
> It appears there is a READ POSITION SCSI command which, if implemented, can
> tell us if we are at the beginning of a partition or not.
>
Yes, but the UNIT ATTENTION tells essentially the same thing (the tape is
rewound at reset). What we must know is if the tape is positioned where
the user thinks it is (wherever that is). I think we need some explicit
or implicit user input (some tape positioning command) for this.
The most difficult problem is how to signal the user that he/she needs to
do explicit positioning. A printk is easy but it does not reach all
users. What is the proper system error code?
Kai
