From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Merritt Subject: SCSI cable advice ? Date: Fri, 7 Feb 2003 09:23:51 -0500 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20030207092351.329ccf01.Scsi@SpoofWorks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org I am redoing my SCSI - LVD/Wide configuration and would appreciate advice on the cabling. I am currently using CRU (removable) dataports with the supplied adaptec internal SCSI LVD/SE WIDE cable. I would like to switch to the CRU backplane product that mounts several of the frame receivers on a (passive) 6 layer backplane. My concern is the short distance between the SCSI drives. The research I have done states that the distance between the drives should be at least 3 times the stub length to avoid "clustering" (also see Annex C in X3T10/1071D). My (limited) understanding is that this configuration is recommended to reduce the effects of reflections from the impedance mismatch at connection points. This implies to me that such backplane products (and typical RAID enclosures in general) are running with reduce margins (especially if external devices are also connected to the SCSI bus) -and- that a conventional cable approach between separate unit is preferred. Is this conclusion correct ??? Thanks, Scott.