Date: Sat, 23 Sep 2000 05:14:30 +0400 (MSD) From: "Aleksandr A.Babaylov" <babolo@links.ru> To: shannon@widomaker.com (Shannon Hendrix) Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: SCSI tape speed Message-ID: <200009230114.FAA09700@aaz.links.ru> In-Reply-To: <20000922185736.C5978@widomaker.com> from "Shannon Hendrix" at "Sep 22, 0 06:57:36 pm"
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Shannon Hendrix writes: > I'm interested in hearing from anyone who uses DAT drives on a DPT SCSI > controller, preferrably with FreeBSD 4.1 and an Intel system. > > I find the speed is very slow, and I know in the past these drives were fine > with FreeBSD, though I can't remember which release now. With my most recent > install of FreeBSD 4.1, I am lucky to get 3MB/minute on a drive and controller > combination that I know can hit 45MB/min. > > Right now, with NetBSD on an old Sparc 5, they still get 20MB/min or better. > > No errors, even large restores are perfect, but take many hours to finish. > > The controller I have is a DPT-2044W, and it currently has the ROM version DPT > suggested for use with tape drives. The drives in question are an Archive > Python 4-tape robot and a Seagate Scorpion. Both are DDS2 drives. I have DDS4 Seagate (IBM) streamer. When I do 'dump something > /dev/sa0' then write is by 1K blocks. The read spead of such a tape is very slow; 'dd if=/dev/sa0 of=/dev/null bs=something' is about 200 Kbyte/sec Just do 'dump something | buffer -s 64K > /dev/sa0' and read from such tape is normal (more than 2 Mbyte/sec, depends on compression) > No load on the DPT except for tapes and a CD-ROM burner. I have 2940UW with lot of devises - I think that low read speed with little blocks is not controller dependant. > I haven't been able to find much information on this particular setup, and > most tape woes seem error related, or related to another platform. -- @BABOLO http://links.ru/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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