Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!att!cbnews!maddog
From: maddog@cbnews.ATT.COM (john.j.tupper)
Newsgroups: comp.sys.hp
Subject: Re: HP9144 cartridge tape drive doesn't stream with HP tape
Keywords: HP9144, cartridge tape, HPUX
Message-ID: <7388@cbnews.ATT.COM>
Date: 12 Jun 89 22:50:58 GMT
References: <234@rdahp.UUCP>
Reply-To: maddog@cbnews.ATT.COM (john.j.tupper)
Organization: AT&T Bell Laboratories
Lines: 27

In article <234@rdahp.UUCP> scott@rdahp.UUCP (Scott Hammond) writes:
>System: HP9000/300 running HPUX 6.2, with HP9144 Cartridge tape drive
>
>I noticed something unusual last week.  I was trying the -S 8 option to
>tcio which specifies a buffer size for talking to the tape drive which
>lets the computer keep up with the tape drive so it can stream (crummy
>explanation but you get the idea, note this only works for certain tape
>drives).  Upon trying it, I discovered it only worked for 3M
>HP-compatible tapes (DC 600HC), and did not work with HP tapes.  This
>also shows up with mediainit.  I tried forcing a mediainit on a 600' HP
>tape, and it took well over 3 hours.  The same on a 3M 600' tape
>required about an hour. 

Each tape is formatted in blocks. The mediainit program goes out checking for
bad blocks and will use spare blocks at the end of the tape as spares (there's
a pool of spare blocks saved for just this purpose). My guess is that the hp
tape you have has some of bad blocks.

[A technicality: I'm not sure mediainit does the sparing of bad blocks, but
 something sure does.]

We also have both hp and 3M tapes and have not noticed any difference between
the two (except for the price :-).

	maddog
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