Subject: Re: HP 1533A DAT drive & Compression
To: Bill Dorsey <email@example.com>
From: Matthew Jacob <firstname.lastname@example.org>
Date: 10/01/2000 00:23:27
probably the NetBSD driver is using the wrong mode page.
On Sun, 1 Oct 2000, Bill Dorsey wrote:
> I was wondering if anyone has successfully used an HP 1533A
> DAT drive with compression turned on. I've filled a 4 gig
> tape 5 times today and every time NetBSD reports the tape is
> full at the 4 gig point. I'm using a 4-gig native capacity
> DDS-2 tape (should give up to 8 gig compressed capacity).
> I'd hope to get better than 1:1 compression on my ufs filesystem.
> I tried setting the DIP switches on the HP drive to force
> compression on. I tried various recommended switch settings
> from HPs web site (which contains very spotty information on
> this drive -- shame on HP) for various operating systems
> including Sun 4.x, SGI, generic PC, and DEC. I also tried
> messing with the NetBSD mt command. If I have the compression
> hard-wired on, mt compress 1 fails, but mt compress 0 succeeds.
> If I have the switches set to allow the computer to select
> compression, then mt compress 1 succeeds. When I do an mt
> status after the mt compress, it always comes back with the
> same thing (and reports the density is 36 -- DDS-2).
> If anyone has any suggestions for other things to try, I'd love
> to hear about them. It would be nice if there were a simple
> way to determine whether compression was working or not without
> filling a tape (I will use 1.3 gig tapes from now in in my
> experiments until I get this working).
> BTW, the hardware is a DEC PWS 433a (Alpha) running NetBSD 1.4Y.
> Bill Dorsey "The unarmed man is not just defenseless --
> email@example.com he is also contemptible." Machiavelli