For some reason the original post was not picked up by my ISP's News
posting but this response was.

Yes, it does sound like HP DDS-DC format.

As a last resort you can disable the DAT drive's internal hardware
compression by removing the drive and setting the swiches. Switch
settings for most HP DAT drives can be found at:

http://www.hp.com/tape/c_switch.html#drive

Switches 1 and 2 are used to configure the way in which data compression
is set for the drive.

Hope this helps.

Good luck.

Bill

BILL R. King, PE
Data Recovery International
2621 Brookridge Drive
Hurst, TX, 76054  USA

Tel 817-281-8901
Fax 817-656-0079

http://www.datarecover.com
[log in to unmask]


Jeff Woods wrote:
>
> At 10:19 PM 4/15/98 +0000, Tracy Johnson wrote:
> >I'm looking at an internal tape drive on a 928 that has "DCLZ" marked on
> >the front of the facade.  I'm assuming it stands for some form of
> >"Lempel-Ziv" hardware compression.
>
> Sounds like it might be an HPC1504B which as you surmise is a DDS-DC drive.
>
> >Is there a way to get around it so I can take a tape to an older machine?
>
> Assuming it's ldev 7, try:
>
>         :devctrl.pubxl.telesup 7;compression=disable
>
> (BTW, I'm doing this from memory.  The script name may be slightly
> different or  be in another group of telesup.  But I know it's in
> "[log in to unmask]@.telesup" on MPE/iX 5.0 and 5.5 releases.)  DEVCTRL is a short,
> easily understood command file which can also enable autoeject after tape
> close and (on 5.5) can put a tape in the drive back online.  I copied the
> command file into PUB.SYS so it's in the default path and I no longer have
> to recall or type the group where it's located.  (I vaguely recall tweaking
> the name slightly too which is why I don't remember the exact spelling.)
>
> >I'm comtemplating CMSTORE but I'm afraid it will compress that too!
>
> It's not the software, but the hardware which would do the compression, and
> yes it would.
>
> >If there isn't a way short of yanking the drive out and setting a switch,
> >I'd be interested in knowing that also.
>
> Using DEVCTRL to set the compression and eject modes for the drive appears
> to only last until the next system restart (or Reset or some such thing).
>
> Good luck!
> --
> Jeff Woods
> [log in to unmask] at Tivoli Systems
> [log in to unmask]   at home  [PGP key available here via finger]
>
> Haiku by Rahul Sonnad:
>    There is a chasm
>    of carbon and silicon
>    the software can't bridge.