From owner-freebsd-current@FreeBSD.ORG Wed Nov 16 14:32:09 2005 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C41ED16A41F for ; Wed, 16 Nov 2005 14:32:09 +0000 (GMT) (envelope-from danny@cs.huji.ac.il) Received: from cs1.cs.huji.ac.il (cs1.cs.huji.ac.il [132.65.16.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 53D8F43D46 for ; Wed, 16 Nov 2005 14:32:09 +0000 (GMT) (envelope-from danny@cs.huji.ac.il) Received: from pampa.cs.huji.ac.il ([132.65.80.32]) by cs1.cs.huji.ac.il with esmtp id 1EcOKV-000HR3-6B; Wed, 16 Nov 2005 16:32:07 +0200 X-Mailer: exmh version 2.7.0 06/18/2004 with nmh-1.0.4 To: Brian Candler In-reply-to: Your message of Wed, 16 Nov 2005 12:27:06 +0000 . Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 16 Nov 2005 16:32:07 +0200 From: Danny Braniss Message-ID: Cc: freebsd-current@freebsd.org Subject: Re: iSCSI initiator driver beta version, testers wanted X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Nov 2005 14:32:09 -0000 Hi Brian, > On Wed, Nov 16, 2005 at 12:45:07PM +0200, Danny Braniss wrote: > > Haven't received much feedback, either it's a piece of s... or > > it's just working fantastic, or ? > > Anyways, I'm planning to be in Basel for BsdConn next week, so if anybody > > has something to say about it, i'm a good listener. > > I for one found the idea very interesting. If we could have an iSCSI target > too, then we would have a complete standards-compliant replacement for GEOM > ggated/ggatec, which might also form the basis of a low-cost SAN. [*] > > However I didn't reply, for two reasons: > > (1) I think you said your code had no error-recovery. In my experience, the > error-recovery code is typically the hardest to write, which implies to me > the code is a long way from complete and therefore not really worth testing. > That is, there's no point testing from the point of view "is this code ready > for production?" when code without error-handling isn't, by definition. > > That's just the impression I got of course, which may be wrong. > I guess I need to clarify some :-), by no error recovery, this is on the iSCSI side, the scsi part - via CAM - is fully error recovarable. the iSCSI protocol has error recovery too, and it's this one that's missing, ie: what happens if the TCP connection falls. so if your network is ok, and no one steps on cables, then it's working fine, no disk corruption, no data loss (FLW - Famous Last Words). i need to test the initiator with different/more targets, it seems that the RFC has more than one interpretation :-) > (2) I didn't fancy setting up a Linux box just so that I had an iSCSI target > :-) no need, we did, and we can crash it :-) > > Regards, > > Brian. > > [*] It might be necessary also to have some magic which maps arbitary > devices under the CAM layer, e.g. so you could share an IDE drive, or a > gvinum volume, as if it were a SCSI device. Or perhaps the iSCSI target can > just be a userland daemon, talking to the CAM layer where the device > supports it, or GEOM otherwise. correct. danny