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Path: sserve!manuel!munnari.oz.au!mips!mips!sdd.hp.com!usc!news
From: merlin@neuro.usc.edu (merlin)
Newsgroups: comp.unix.bsd
Subject: rdump utility -- current blocking factor = 2 should be = 20/64/126
Date: 26 Jul 1992 16:27:42 -0700
Organization: University of Southern California, Los Angeles, CA
Lines: 36
Sender: merlin@neuro.usc.edu (merlin)
Message-ID: <l76d7eINN1ad@neuro.usc.edu>
NNTP-Posting-Host: neuro.usc.edu
While 4.3BSD-NET2/386BSD says it knows about 'drum' devices (anyone seen
one of these since the early 1960's -- we had one at cdc analog digital
division la jolla on cdc 1700's for priority based swapping in real time
applications under msdos -- still one of our development teams somehow
managed to blow up two percent of the us oil refining capacity by opening
a high test aviation fuel line in a loading dock which was supposed to
contain a connected tanker truck -- but instead the fuel hit a hot steam
line -- and, well, to say the least the photographs were spectacular --
well, enough history, back to my question) --
Does anyone have a modification of the dump/rdump utility which permits
more flexible blocking of records written to tape. The current rdump
document says it writes 1024 byte blocks to tape -- this might be less
than optimal for most tape (particularly cartridge based) systems. One
vendor's manual page for rdump suggests there should be a parameter:
b <blocking factor> which defaults to 20 blocks per write -- but
should be set to 64 blocks per write for 6250+ BPI tapes -- and
should be set to 126 blocks per write for cartridge tapes. The
blocking factor is specified in terms of 512 byte blocks.
Of course, rrestore would have to be similarly modified.
The problem is that streaming tapes like their data in big chunks -- else
the spend their day winding tape back and forth every few seconds -- this
change would make rdump stype tape backups run much faster.
Thanks, AJ
p.s. If I use rrestore from the initial bootable floppy what user id will
my sun system see attached to the rrestore request?
p.s. Is there such a thing as single user mode in 386bsd? Or is it just
multiple user mode with no other users allowed to log in? How does one
reach single user mode if one wants to do so? Is there any way to very
gracefully shut down nfs other than 'ifconfig <adaptor> down'.