From owner-freebsd-hackers Wed Mar 22 00:42:04 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id AAA27013 for hackers-outgoing; Wed, 22 Mar 1995 00:42:04 -0800 Received: from ref.tfs.com (ref.tfs.com [140.145.254.251]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id AAA27006; Wed, 22 Mar 1995 00:42:03 -0800 Received: (from phk@localhost) by ref.tfs.com (8.6.8/8.6.6) id AAA04565; Wed, 22 Mar 1995 00:41:56 -0800 From: Poul-Henning Kamp Message-Id: <199503220841.AAA04565@ref.tfs.com> Subject: Why IDE is bad To: hackers@FreeBSD.org Date: Wed, 22 Mar 1995 00:41:56 -0800 (PST) Cc: faq@FreeBSD.org Content-Type: text Content-Length: 1272 Sender: hackers-owner@FreeBSD.org Precedence: bulk I just made a simple test, this shows why IDE is inferior to SCSI for FreeBSD: Western Digital 540 Caviar EIDE disk on IDE controller: ------------------------------------------------------- dd if=/dev/rwd0d of=/dev/null bs=64k count=8253 8253+0 records in 8253+0 records out 540868608 bytes transferred in 240 secs (2253619 bytes/sec) Here is what "systat" tells me: 2.0%Sys 82.0%Intr 0.5%User 0.0%Nice 15.6%Idle | | | | | | | | | | =+++++++++++++++++++++++++++++++++++++++++ Quantum Empire 2100 SCSI-II disk on VL-buslogic controller: ------------------------------------------------------------- dd if=/dev/rsd0d of=/dev/null bs=64k count=8253 8253+0 records in 8253+0 records out 540868608 bytes transferred in 110 secs (4916987 bytes/sec) Here is what "systat" tells me: 5.6%Sys 20.6%Intr 0.2%User 0.0%Nice 73.6%Idle | | | | | | | | | | ===++++++++++ CONCLUSION: ----------- The SCSI-controller transfers twice as much data in the same time, and uses only 25% of the CPU resources the IDE-controller needs. -- Poul-Henning Kamp -- TRW Financial Systems, Inc. 'All relevant people are pertinent' && 'All rude people are impertinent' => 'no rude people are relevant'