From owner-freebsd-scsi Sun Aug 4 14:11:41 2002 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 7012F37B400; Sun, 4 Aug 2002 14:11:39 -0700 (PDT) Received: from aslan.scsiguy.com (aslan.scsiguy.com [63.229.232.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9F67143E6A; Sun, 4 Aug 2002 14:11:38 -0700 (PDT) (envelope-from gibbs@scsiguy.com) Received: from scsiguy.com (localhost [127.0.0.1]) by aslan.scsiguy.com (8.12.5/8.12.5) with ESMTP id g74LBVSY063691; Sun, 4 Aug 2002 15:11:31 -0600 (MDT) (envelope-from gibbs@scsiguy.com) Message-Id: <200208042111.g74LBVSY063691@aslan.scsiguy.com> To: Zhihui Zhang Cc: freebsd-hackers@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: transaction ordering in SCSI subsystem In-Reply-To: Your message of "Sun, 04 Aug 2002 16:28:26 EDT." Date: Sun, 04 Aug 2002 15:11:31 -0600 From: "Justin T. Gibbs" Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org > >While reading the document on FreeBSD SCSI subsystem, I am wondering what >does guaranteed transaction ordering mean? Does it have anything to do >with I/O ordering, tagging, write caching, etc.? Yes, yes, and yes. CAM guarantees that transactions are queued to the device in the order they were queued to CAM. Even if an error recovery action occurs, I/O is retried/resumed in order once the device is recovered. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message