From owner-freebsd-scsi Fri Mar 12 15:13: 0 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from palrel3.hp.com (palrel3.hp.com [156.153.255.226]) by hub.freebsd.org (Postfix) with ESMTP id C7D9115093 for ; Fri, 12 Mar 1999 15:12:46 -0800 (PST) (envelope-from darrylo@sr.hp.com) Received: from srmail.sr.hp.com (srmail.sr.hp.com [15.4.45.14]) by palrel3.hp.com (8.8.6 (PHNE_14041)/8.8.5tis) with ESMTP id PAA11707 for ; Fri, 12 Mar 1999 15:12:45 -0800 (PST) Received: from mina.sr.hp.com by srmail.sr.hp.com with ESMTP (1.37.109.16/15.5+ECS 3.3) id AA281080346; Fri, 12 Mar 1999 15:12:26 -0800 Received: from localhost (darrylo@mina.sr.hp.com [15.4.42.247]) by mina.sr.hp.com with ESMTP (8.8.6 (PHNE_14041)/8.7.3 TIS 5.0) id PAA12555 for ; Fri, 12 Mar 1999 15:12:25 -0800 (PST) Message-Id: <199903122312.PAA12555@mina.sr.hp.com> To: freebsd-scsi@FreeBSD.ORG Subject: Re: SCSI disk oddities and Buslogic problems.. Reply-To: Darryl Okahata In-Reply-To: Your message of "Fri, 12 Mar 1999 09:43:00 +0100." <3236.921228180@verdi.nethelp.no> Mime-Version: 1.0 (generated by tm-edit 1.1.1.1) Content-Type: text/plain; charset=US-ASCII Date: Fri, 12 Mar 1999 15:12:25 -0800 From: Darryl Okahata Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org sthaug@nethelp.no wrote: > Chris Csanady wrote: > > In this case, I have found that while running the following commands that > > the data transfer is very erratic. > > > > dd if=/dev/rda2s3 of=/dev/null bs=128k (or any place on the disk..) > > > > iostat -w 1 da2 > > No problem with a 9 GB model here. Typical iostat output: I have seen strange things with 3.1-RELEASE (I've yet to try -current), and tagged queueing. Using 3.1-RELEASE, an Adaptec 7895 controller (built into my Gigabyte 6BXDS motherboard) and two IBM Ultrastar 9ES drives striped together using vinum, I get strange performance numbers using iozone (yeah, iozone isn't very good for benchmarking striped drives, but I'm just using it as a zero-th order gauge). Individually (if I do not use vinum and just newfs a single drive), I get around 11MB/s write, and 13MB/s read. No problem here. If I stripe the drives together using vinum, and use the default newfs values, I get something like 3.7MB/s write, and 16MB/s read. The write throughput sucks. If I run newfs with 4K frag sizes, the write throughput jumps up to around 7MB/sec. Better, but still not great. However, if I go into the BIOS and disable SCSI disconnect, the write throughput jumps back up to 11MB/s. Much better, but disabling disconnects kinda defeats the purpose of striping .... The only thing I can think of is that tags are somehow involved, as disabling disconnects also disables tags. However, one slightly unusual thing about the striped drives is that one drive is a plain fast/wide disk ("IBM DDRS-39130W S97B"), and the other is the LVD version running in single-ended mode ("IBM DDRS-39130D DC1B"), but this shouldn't matter. -- Darryl Okahata darrylo@sr.hp.com DISCLAIMER: this message is the author's personal opinion and does not constitute the support, opinion, or policy of Hewlett-Packard, or of the little green men that have been following him all day. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message