Date: Tue, 30 Jan 1996 20:18:50 -0800 (PST) From: pete@pelican.com (Pete Carah) To: msmith@atrad.adelaide.edu.au (Michael Smith) Cc: questions@freebsd.org Subject: Re: QIC-3080: density & length Message-ID: <m0thU0R-0000SMC@pelican.com> In-Reply-To: <199601250119.LAA28651@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Jan 25, 96 11:49:04 am
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Michael Smith writes: > Pete Carah stands accused of saying: > > >> I have purchased a Conner TSM4000R SCSI tape backup unit. I have > > >> found this unit mentioned several times in questions in the mail > > >> archives, but unfortunately the replies must have been sent > > >> directly, and not forwarded to the list. > > > > > >Odd, I've read lots of people saying that they're lemons. Sorry. > > > > Well, I was never able to get one to stream on a SS1000 that easily > > Ok, that settles it for me. 8) FBSD may be better; the DMA limit is higher. On the other hand it's less than half as fast as a DLT so if the DLT can stream at a 64k blocksize (-b 126) I'd hope the Conner would. > > If you need speed and don't worry about $$$ I'd recommend a DLT, > > though I've never tried one (directly; with /etc/rmt it won't > > stream from either fbsd or a SS20 but I'd expect that) on freebsd > > either :-) As long as fbsd's tape driver can handle variable > > blocksize it should be fine. > > That's really strange; we use rmt for all our backups (Sony SDT-5200) > and it streams almost all of the time. The backup server's just a > 486 with an NE2000 in it, and it's often running X. > You may be loaded more heavily though... Well, the Sun QIC tape driver has a DMA limit of 64k; that may have something to do with it. The DAT/DLT/Reel driver goes longer but then you get big blocks that things like SGI's can't read :-( (and the DLT still streams with gnu tar at -b 126). The usual conditions for our rmt dumps are ss20 -> SS1000, both otherwise unloaded (well, the ss20 is sometimes running X with no other activity). (or FBSD (P100) -> SS1000; still won't stream and the net is not very busy either). The Sun console driver is very slow; if you dump "tar cvf /dev/rmt/xxx" a full-system dump goes almost twice as fast with the tty on X... That is not relevant for our video streams though (1/2 gig single files). I'm likely to use a DAT for backup at home and my isp friends; the choices at the moment are Conner (archive) (which SGI distributes) or HP (one of two models; I don't know the difference.) Currently at home I use a Wangtek QIC525 drive; it works great. -- Pete
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