Date: Mon, 20 Apr 1998 10:01:32 -0500 From: "Jaime Bozza" <wheelman@nuc.net> To: "Mike Smith" <mike@smith.net.au>, "Berend de Boer" <berend@pobox.com> Cc: <stable@FreeBSD.ORG> Subject: RE: best sd0 flags ? (was wdc0) Message-ID: <000801bd6c6d$34866560$0f3d31cc@electron.nuc.net> In-Reply-To: <199804200531.WAA04185@antipodes.cdrom.com>
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> As Bruce mentioned, you should use the raw device: > > azaria# dd if=/dev/sd1 of=/dev/null bs=1m count=20 > 20+0 records in > 20+0 records out > 20971520 bytes transferred in 9.182458 secs (2283868 bytes/sec) > azaria# dd if=/dev/rsd1 of=/dev/null bs=1m count=20 > 20+0 records in > 20+0 records out > 20971520 bytes transferred in 2.571084 secs (8156684 bytes/sec) > > for a similar configuration (DCAS34330UW, PII/337, AHA2940UW) I decided to try the same thing. Always been curious about the performance. %dd if=/dev/sd0 of=/dev/null bs=1m count=20 20+0 records in 20+0 records out 20971520 bytes transferred in 4.835489 secs (4337001 bytes/sec) %dd if=/dev/rsd0 of=/dev/null bs=1m count=20 20+0 records in 20+0 records out 20971520 bytes transferred in 2.201617 secs (9525508 bytes/sec) I did it a few times, and have seen slightly higher and slightly lower. 9M seems to be about an average for me. That particular system is a SEAGATE ST34555W 0930 (Seagate Hawk), Pentium 133, Adaptec 2940W (Not a(n) UW, though the drive is an UltraWide) Another system with a 2940UW/P5-133/SEAGATE ST15150W 0011 (One of the original Seagate Barracudas!) meson# dd if=/dev/sd0 of=/dev/null bs=1m count=20 20+0 records in 20+0 records out 20971520 bytes transferred in 8.065788 secs (2600058 bytes/sec) meson# dd if=/dev/rsd0 of=/dev/null bs=1m count=20 20+0 records in 20+0 records out 20971520 bytes transferred in 3.049587 secs (6876839 bytes/sec) Jaime Bozza Nucleus Communications, Inc. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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