SUMMARY: Slow DDS-2 DAT drive - why?

From: Charles Hawkins (ceh@eng.cam.ac.uk)
Date: Fri Dec 23 1994 - 07:50:32 CST


The original Question:

> I have just got a Sony DDS-2 DAT drive that is connected to a Sparc 2
> running 4.1.3. The problem I have is that I only get write rates of
> around 9k per second. This is needless to say, just a little
> disappointing for a drive that (I believe) should be capable of around
> 400k/s minimum.
>

Thanks to the people who responded, including Laurel Arthur and some
others whose names I've forgotten.

This from Laurel:
>
> Yes - SunOS4.1.3 doesn't have any built-in information about DAT drives.
> So when you plug on into it, it will talk to the drive, but it treats it
> as a character device - result, very slow transmission rates! I had the
> same problem with a WangDAT tape drive when I first got it.
>
> Look at the scsi tape tables in /usr/kvm/sys/scsi/targets and add entries
> for your DAT drive (sorry, I don't have the information at my fingertips;
> but there should be details in your system manuals). Build a new kernel
> (you don't need to change the configuration in any way) and you should
> see dramatically improved performance.
>
And the entry needed for the Sony SDT-5000 in
/usr/kvm/sys/scsi/targets/st_conf.c is

/* Sony Model SDT-5000 4mm Helical Scan 4GB drive */
/* Added by K. A. Noll 1 Jun 1994 */
{
        "SONY", 24, "SONY SDT-5000 ",
        ST_TYPE_SONYDAT, 1024,
        (ST_VARIABLE | ST_BSF | ST_BSR | ST_LONG_ERASE),
        5000, 5000,
        { 0x00, 0x8C, 0x8C, 0x8C },
        { 0, 0, 0, 0 }
},

Also I neeeded to add this to /usr/kvm/sys/scsi/targets/stdef.h

#define ST_TYPE_SONYDAT 0x2a

Thanks All,

Happy Christmas,

Charles Hawkins
Research Systems Support

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