From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Linton Subject: Re: [Bug 7026] CD/DVD burning with USB writer doesn't work Date: Wed, 6 Dec 2006 17:55:07 -0600 Message-ID: <200612061755.08213.jli@greshamstorage.com> References: <45774927.8090204@cs.wisc.edu> <200612061742.27884.jlinton@greshamstorage.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from austin.greshamstorage.com ([216.143.252.250]:3723 "EHLO austin.greshamstorage.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S937820AbWLFXzg (ORCPT ); Wed, 6 Dec 2006 18:55:36 -0500 In-Reply-To: <200612061742.27884.jlinton@greshamstorage.com> Content-Disposition: inline Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Mike Christie Cc: linux-scsi@vger.kernel.org, dougg@torque.net On Wednesday 06 December 2006 17:42, Jeremy Linton wrote: > On Wednesday 06 December 2006 16:50, Mike Christie wrote: > > > For iscsi, we could negotiate a value like MaxBurstLength which says > > > don't send commands with a payload larger than that size. I would guess > > > other transports have something similar. We have to check or make sure > > ... > > > Oh yeah the exception I am thinking about may not be max sectors exactly > > but something close like iscsi's MaxBurstLength limit. Maybe iscsi LLDs > > are supposed to be translating that iscsi limit to max_sectors in which > > case we are talking about the same thing. For this limit we do not want > > Sort of off topic, but the iSCSI MaxBurstLength doesn't set the max > transfer size, it simply is the amount of data that can be sent without a > R2T. If the transfer is larger then you have to wait for the R2T. In > practice it ends up controlling the _minimum_ amount of buffer space that > needs to be available _before_ the transfer starts, otherwise performace > sucks. Whops, Slight clarification, the MaxBurstLength is the max sent between R2T's what I described above is closer to the FirstBurstLength. What you guys are describing might better be the MaxRecvDataSegmentLength, but not really since that parameter should be hidden within the iSCSI driver.