Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: tardis!jms@tymix.tymnet.com (Joe Smith)
Newsgroups: comp.sys.sun
Subject: Re: cartridge tape designators
Message-ID: <705@brazos.Rice.edu>
Date: 31 Jul 89 19:50:10 GMT
Sender: root@rice.edu
Organization: Sun-Spots
Lines: 41
Keywords: Hardware
Approved: Sun-Spots@rice.edu
X-Sun-Spots-Digest: Volume 8, Issue 91, message 3 of 16

In article <114@brazos.Rice.edu> stiatl!meo@gatech.edu (Miles O'Neal) writes:
>X-Sun-Spots-Digest: Volume 8, Issue 70, message 1 of 15
>
>In article <4107@kalliope.rice.edu> eli@chipcom.chipcom.com writes:
>| X-Sun-Spots-Digest: Volume 8, Issue 49, message 1 of 11
>| 
>| what is the difference between /dev/rst0 and /dev/rst8
>| and likewise between           /dev/nrst0 and /dev/nrst8
>
>The difference is the tape format. I don't remember the exact definitions,
>but basically, the 0 devices are for 45MB tape formats, and the 8 devices
>use the 60MB formats. They aren't interchangeable.
>
>Miles

I, too, would like to know the difference between rst0 and rst8 on 1/4
inch tape.  The only references I have found are on page 84 of the
"Network and System Administration" manual, part 800-1733-10, Rev A, May
1988.

rst0 = QIC-11, 9 tracks, 45 Mbytes on 450 ft, 60 Mbytes on 600 ft tape
rst8 = QIC-24, 9 tracks, 45 Mbytes on 450 ft, 60 Mbytes on 600 ft tape

This implies that the amount of storage depends only on the length of tape
and not whether you specify /dev/rst0 vs /dev/rst8.

I have been told that the tape drive always stores 512 bytes per tape
block.  There is a flag bit to say whether more data follows, a count of
valid bytes, and a checksum for the block.  Is it true that QIC-11 and
QIC-24 store the same amount of data on the tape, and just have different
standards for encoding the length and checksum?

Which format is recommended for doing dumps?  Which format should be used
for interchanging data with other systems?  In other words: when should I
use rst0 and when should I use rst8?


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