From: rvdp@sow.econ.vu.nl (Ronald van der Pol)
Newsgroups: comp.unix.sysv386
Subject: Re: how to write 525MB to Wangtek 525ES on Dell 2.1?
Date: 19 Aug 92 20:01:39 GMT
Organization: SOW-VU, Amsterdam, The Netherlands

grog@adagio.UUCP (Greg Lehey) writes:

>In article <rvdp.714046351@yam> rvdp@sow.econ.vu.nl (Ronald van der Pol) writes:
>>larry@gator.rn.com (Larry Snyder) writes:
>>
>>>rvdp@sow.econ.vu.nl (Ronald van der Pol) writes:
>>
>>>>We have a Wangtek 525ES SCSI cartridge tape drive which should be
>>>>able to write various formats (525, 250, 150 MB). But how do you
>>>>choose the format? There don't seem to be different special files
>>>>for different formats. So how should it be done?
>>
>>>I belive the tape and drive determine this -- ie: put a 150 meg tape
>>>in the drive will yield 250 megs, a 60 meg will yield 120 megs
>>
>>I used the Wangtek 5525ES tape drive and a DC6525 tape. The script
>>wrote 9 25MB files and 13 records of the 10th file. So about 238 MB
>>was written (with 9 FileMarks?). After a 'mt rewind' and a 'mt fsf 9'
>>the tape looks to be  positioned at the end of the media. So how much
>>is written to the tape, 250 MB or 525 MB?

>Maybe we should step back and look at this from a different angle. In
>particular:

>- What the driver does depends on how it's programmed. I don't know
>  Dell at all, but it is probably similar in behaviour to other SysV
>  ports. These will determine the format of a tape when called upon to
>  read it (this is the reason for the apparently non-productive noises
>  when it starts reading). In the case of writing, it will take a
>  default value.

>- The amount that the default writes depends on the length of the tape
>  (you weren't expecting that, were you?). A DC6525 tape is 1000'
>  long, a DC6150 tape is 600' long. Accordingly, if you write to a
>  DC6525 in QIC-150 mode, you will get about 250 MB on the tape - as
>  your experiment proves.

>- Despite what many people have said on the subject, your assumption
>  is correct: the normal way to select densities is via a different
>  minor device number, which is usually attached to a different
>  special device. This is where I can't help you: your system
>  documentation should help. In my (by no means exhaustive)
>  experience, people haven't gone to much trouble to support QIC-525
>-- 
>Greg Lehey                       | Tel: +49-6637-1488              
>LEMIS                            | Fax: +49-6637-1489
>Schellnhausen 2, W-6324 Feldatal, Germany
>*** NOTE ***: Headers are mangled - reply to grog%lemis@Germany.EU.net

Thanks, that clears up a lot. Dell Issue 2.1 (System V Release 4) has
the following special files in /dev/rmt:

crw-rw-rw-   1 root     root      15,  0 Jul 31 12:39 c0s0
crw-rw-rw-   1 root     root      15,  1 Aug 17 12:10 c0s0n
crw-rw-rw-   1 root     root      15,  3 Jun 11 17:14 c0s0nr
crw-rw-rw-   1 root     root      15,  2 Jun 11 17:14 c0s0r

The manual qt(7) says:


	 NAME
	       qt - QIC	cartridge magnetic tape	streamer interface

	 SYNOPSIS

		     /dev/rmt/c0s0n    no rewind on close, no retension	on
				       open
		     /dev/rmt/c0s0     rewind on close,	no retension on
				       open
		     /dev/rmt/c0s0nr   no rewind on close, retension on
				       open
		     /dev/rmt/c0s0r    rewind on close,	retension on open

	       These files refer to the	Wangtek	PC-36 Controller and the
	       QIC-24/QIC-02 basic cartridge tape streamer.  Only raw
	       character interface files are provided.

We specifically bought a Dell computer and a Wangtek 5525ES tape *from
Dell*, because we wanted to have a system that is fully supported by
Dell. The system we already had is a Compaq with Exabyte tape drive.
And Dell doesn't (officially) support Exabyte tape drives.

So again, (not asking how, but rather) *can I write 525 MB to an
Wangtek 5525ES tape drive on Dell Issue 2.1*?

Is Dell back on the net again???

--
Ronald van der Pol
rvdp@sow.econ.vu.nl
Newsgroups: comp.unix.sysv386