ayk@camex.camex.com.COM (Andrew Kobayashi) (11/01/90)
We've gotten some 4mm evaluation units from WangDAT and Dilog. The former is the WangDAT 2600, which can cram up to 2.6 gigabytes on one 60 meter long 4mm tape by virtue of a compression chip. (Your mileage may vary. :-) The latter is call a DAT Stacker, and it has a carriage that holds a stack of eight 4mm tapes. The drive itself writes a "mere" 1.3 gigabytes per 60 meter tape, for a total capacity of around *ten* gig. Sheesh. The problem i'm running in to is apparently the old bugaboo of "conflicting standards". Both drives claim to adhere to the DDS standard. And indeed i can make a tape on the WangDAT (in uncompressed mode) that the Dilog happily reads. But i cannot read tapes made on the Dilog unit on the WangDAT. I've got calls in to tech reps at both manufacturers, but what i am afraid is going to happen is a lot of finger-pointing about incompatible implementation of the "standard". I was wondering if anyone out there had any real information, or will i have to rely on the manufacturers to tell me the truth about each other? :-) I make the standard disclaimer about vested interest in either unit. --Andrew Kobayashi CAMEX, Boston, MA, USA ...!uunet!camex!ayk, ayk@camex.com
mark@hpcpbla.HP.COM (Mark Simms) (11/09/90)
Hewlett Packard is the keeper of the DDS standard. If you have any problems with DDS compatibility you should contact Peter Bramhall at Hewlett-Packard Computer Peripherals Division Filton Road Bristol BS12 6QZ United Kingdom Phone: +44-272-799910 ext 22346 Fax: +44-272-236091 email: peteb%hpcpbla@hplb.hpl.hp.com Hewlett Packard will probably reserve the right to use any information discovered about any non-compliance with the DDS specification in marketting its own DDS products. Mark Simms ---------------------------------------------------------------------- Opinions expressed are my own and are not intended to be an official statement by Hewlett-Packard Company ---------------------------------------------------------------------- Name: Mark Simms Profession: Software Engineer Occupation: Research and Development Organization: Hewlett-Packard Computer Peripherals Division Unix-mail: mark%hpcpbla@hplb.hpl.hp.com Address: Filton Road, Bristol BS12 6QZ, United Kingdom Phone: +44-272-799910x22174 Fax: +44-272-236091 ----------------------------------------------------------------------
mike@flame.et.iupui.edu (P. Michael Haffley) (11/13/90)
The problem is not with Drives, but with the Device Drivers you are using
with the drives. Both Drives follow the DDS format, but not all device
drivers do. For example, the tape device driver that comes with SunOS 4.1
does not support the 4mm DAT Drives, but one can still hook up the some
DAT Drives and use the st device. Since the 4mm DAT Drive is not supported,
Sun's device drives reverts to the default Quarter Inch tape format, which
uses only 512 byte block size. The DAT Drives by default use 1024 byte block
size and can automatically switch the block size that tape had been writen
for. Sun's device driver will always force 512 byte block size even if the
tape had been written at 1024 byte block size. Thus, a tape written using
a device driver especially for the the DAT drive will perform optimally and
write 1K block size, but the tape can not be read by the same DAT drive using
Sun's st device because it will only try to read at 512 byte block size and
fail. Since Sun does not officially support the DAT drive, I would not use
the SCSI tape device driver supplied by Sun with a DAT Drive.
_ __ _ _ _ _ _ , _
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/> /> /
</ </ '
P. Michael Haffley
mike@ethome.iupui.edu
(ames,rutgers,pur-ee,att)!ethome.iupui.edu!mike
--
_ __ _ _ _ _ _ , _
' ) ) ' ) ) ) / // ' ) / /) /) //
/--' / / / o _. /_ __. _ // /--/ __. // // // _ __ ,
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P. Michael Haffley
mike@ethome.iupui.edu
(ames,rutgers,pur-ee,att)!ethome.iupui.edu!mikemike@ethome.iupui.edu (P. Michael Haffley) (11/13/90)
Subject: Re: WangDAT/Dilog compatability
Date: 12 Nov 90 13:45:59
The problem is not with Drives, but with the Device Drivers you are using
with the drives. Both Drives follow the DDS format, but not all device
drivers do. For example, the tape device driver that comes with SunOS 4.1
does not support the 4mm DAT Drives, but one can still hook up the some
DAT Drives and use the st device. Since the 4mm DAT Drive is not supported,
Sun's device drives reverts to the default Quarter Inch tape format, which
uses only 512 byte block size. The DAT Drives by default use 1024 byte block
size and can automatically switch the block size that tape had been writen
for. Sun's device driver will always force 512 byte block size even if the
tape had been written at 1024 byte block size. Thus, a tape written using
a device driver especially for the the DAT drive will perform optimally and
write 1K block size, but the tape can not be read by the same DAT drive using
Sun's st device because it will only try to read at 512 byte block size and
fail. Since Sun does not officially support the DAT drive, I would not use
the SCSI tape device driver supplied by Sun with a DAT Drive.
_ __ _ _ _ _ _ , _
' ) ) ' ) ) ) / // ' ) / /) /) //
/--' / / / o _. /_ __. _ // /--/ __. // // // _ __ ,
/ o / ' (_<_(__/ /_(_/|_</_</_ / (_(_/|_//__//__</_</_/ (_/_
/> /> /
</ </ '
P. Michael Haffley
mike@ethome.iupui.edu
(ames,rutgers,pur-ee,att)!ethome.iupui.edu!mike
--
_ __ _ _ _ _ _ , _
' ) ) ' ) ) ) / // ' ) / /) /) //
/--' / / / o _. /_ __. _ // /--/ __. // // // _ __ ,
/ o / ' (_<_(__/ /_(_/|_</_</_ / (_(_/|_//__//__</_</_/ (_/_