From owner-freebsd-scsi@FreeBSD.ORG Tue Jun 14 07:36:37 2005 Return-Path: X-Original-To: freebsd-scsi@freebsd.org Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E1F8016A41C for ; Tue, 14 Jun 2005 07:36:37 +0000 (GMT) (envelope-from glenn@antimatter.net) Received: from cobalt.antimatter.net (cobalt.antimatter.net [69.55.224.239]) by mx1.FreeBSD.org (Postfix) with ESMTP id BDD8843D49 for ; Tue, 14 Jun 2005 07:36:37 +0000 (GMT) (envelope-from glenn@antimatter.net) Received: from glenn-mobile.antimatter.net (cpe-66-27-86-22.san.res.rr.com [66.27.86.22]) (authenticated bits=0) by cobalt.antimatter.net (8.13.4/8.13.4) with ESMTP id j5E7aZjc017778 (version=TLSv1/SSLv3 cipher=DES-CBC3-SHA bits=168 verify=NO); Tue, 14 Jun 2005 00:36:35 -0700 Message-Id: <6.1.0.6.2.20050614003252.0bfc5eb0@cobalt.antimatter.net> X-Sender: lists@cobalt.antimatter.net X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 Date: Tue, 14 Jun 2005 00:34:48 -0700 To: freebsd-scsi@freebsd.org From: Glenn Dawson Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Subject: Re: Accessing SCSI-Devices >2TB X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 Jun 2005 07:36:38 -0000 At 09:36 PM 6/13/2005, Scott Long wrote: >>It is a SCSI RAID controller, but the interface to the OS is a block >>interface, not a SCSI interface (*). It isn't routed through the SCSI >>layer, since that wouldn't really help it that much. >>(*) There is a SCSI passthrough interface for some aac controllers that >>can be enabled via the aacp driver. >>Ken > >And the aacp device causes many more problems than it solves, so I'll >likely be disabling it soon. It only provides simple userland SCSI access >to cdroms and tape drives, anyways. This is a little OT for this thread, but I'm currently trying to solve a problem which might be related to the aac driver, so I'll toss this out there and see if anyone has any ideas for me. It trying to make the transition from 4.x to 5.x I've noticed that performance of the md(4) (in 5.x) driver seems to be much worse than the vn(4) driver under 4.x. Here's the scenario: A pair of mirrored disks on an adaptec 2120S using the aac(4) driver is being used to house files that are the backing store for a number of virtual disks. Each file is typically about 4GB. Under 4.11 using the vn(4) driver I see throughput of about 17MB/sec when writing to one of the virtual disks (using dd). Under 5.4 using the md(4) driver I only see throughput of about 7MB/sec when writing to the virtual disk. Tests were run using the exact same hardware. Is this something that might be caused by the aac(4) driver? or should I be looking at md(4)? Sorry for sending this twice..accidently sent before I was finished. -Glenn >Scott >_______________________________________________ >freebsd-current@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-current >To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org"