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From: dricejb@drilex.UUCP (Craig Jackson drilex1)
Newsgroups: comp.unix.admin
Subject: Re: Dumping to an exabyte tape drive
Summary: The video systems are different
Keywords: Exabyte dump args
Message-ID: <15425@drilex.UUCP>
Date: 7 Sep 90 20:06:54 GMT
References: <1990Aug29.143657.20588@siesoft.co.uk> <877@iiasa.UUCP> <25394@shamash.cdc.com> <882@iiasa.UUCP>
Organization: DRI/McGraw-Hill, Lexington, MA
Lines: 41

In article <882@iiasa.UUCP> wnp@iiasa.UUCP (wolf paul) writes:
>In article <25394@shamash.cdc.com> zeke@shamash.cdc.com (Robert Scott) writes:
>>	
>>	Example for a full dump command to a Sony P6-120 tape using
>
>Could someone explain these tape designations? Over here, I cannot
>find P6 tapes, only P5. We are using TDK P5-90 tapes, the genuine
>Exabyte "EXATAPE" cartridge which was packaged with our SUN-supplied
>drive does not have any "P" designation, but is labelled, "112m".

The tapes are labelled differently because the capacity of a given
number of meters of tape depends on the video system being recorded.
The U.S. and Japan use the NTSC color video system.  Europe uses either
the PAL or the SECAM color video system.  (I think one is basically
British in origin, and one French.)  The PAL system, in particular,
uses 625 lines/frame and 25 frames/second.  NTSC uses 525 lines and 30 frames.
However, there are even greater differences in the way color is recorded.
(I'm told that PAL color is much better.)

These differences seem to add up to the fact that you can get 120 minutes
of NTSC video on less tape than is required to hold 90 minutes of PAL
video.  The tape manufacturers want to express the length in minutes,
not feet or meters, therefore the tapes are labelled differently on
different continents.

I suspect that "P5" and "P6" mean something to a tape standards committee,
but for our purposes they simply indicate which time/length calculation
to use.

>What would be a convenient way under UNIX (SunOS) to actually
>determine the capacity of any such tape?

Our Exabyte vendor (Delta Microsystems) included a table giving all of the
capacities....

>Wolf N. Paul, IIASA, A - 2361 Laxenburg, Austria, Europe
>INTERNET: wnp%iiasa.at@uunet.uu.net      BITNET: tuvie!iiasa!wnp@awiuni01.BITNET
-- 
Craig Jackson
dricejb@drilex.dri.mgh.com
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