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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.ecn.uoknor.edu!news.wildstar.net!news.ececs.uc.edu!newsxfer.itd.umich.edu!newsxfer3.itd.umich.edu!su-news-hub1.bbnplanet.com!news.bbnplanet.com!news.pbi.net!samba.rahul.net!rahul.net!a2i!fmc.a2i!fmc From: Frank McConnell <fmc@rahul.net> Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Need help with dump parameters Date: 16 Mar 1997 07:34:05 GMT Organization: File under Psychedelia Lines: 39 Message-ID: <5gg7pd$70l@samba.rahul.net> References: <5g87ob$arr@sloth.swcp.com> <5ga3c1$pp@uriah.heep.sax.de> NNTP-Posting-Host: waltz.rahul.net NNTP-Posting-User: fmc Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:37131 J Wunsch <joerg_wunsch@uriah.heep.sax.de> wrote: >In FreeBSD 2.2 and above, there will be the `a' option, meaning to >make all tape length calculations `automatic' (which doesn't mean >anything else than not doing tape length calculations at all, but rely >on the tape driver reporting EOF). Thank you. This will be greatly appreciated. This is one of those things that has bugged me for years, not just in FreeBSD but in just about any BSDish Un*x with dump. For about the last 20 years, I've been doing stuff with computer systems that could see the EOT mark (a little reflective sticker) placed near the end of the obligatory nine-track tape. When your tape-writing program gets the EOT notification, it is expected to write its tape volume trailer, rewind the tape, put it offline, and ask on the obligatory operator's console for the next tape to be mounted. So why does dump instead have all this cruft for letting, um I mean making the operator tell it how much stuff to write on a tape? It just seems to me that it would have been so much easier to look for and handle the EOT mark in the first place. Thanks for making it happen. For bonus fun I have been working out dump parameters on a 2.1.5 system. The man page description of the B and b options is confusing, maybe because I think in terms of records, blocks, and volumes; so to me it seems to indicate that b sets the record size and B sets the number of those records that you expect to fit on a volume. That ain't so, from looking at the code: the dump record size is fixed at 1KB, B sets how many of those you can fit on one volume, and b sets how many you want to write in one chunk or block or tape record. Or at least, that is a better model for working out what parameters to put on the command line. How do things like blocking factors, maximum block sizes, and inter-record gaps work on DDS tapes? I used to know this sort of stuff for nine-track tapes, but haven't run across a good explanation of how it works for newer cartridge media. -Frank McConnell