From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266871AbUGLPX3 (ORCPT ); Mon, 12 Jul 2004 11:23:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266876AbUGLPX2 (ORCPT ); Mon, 12 Jul 2004 11:23:28 -0400 Received: from web52507.mail.yahoo.com ([206.190.39.132]:39844 "HELO web52507.mail.yahoo.com") by vger.kernel.org with SMTP id S266874AbUGLPXL (ORCPT ); Mon, 12 Jul 2004 11:23:11 -0400 Message-ID: <20040712152310.22995.qmail@web52507.mail.yahoo.com> Date: Mon, 12 Jul 2004 08:23:10 -0700 (PDT) From: Shobhit Mathur Subject: cmd_per_lun vs can_queue To: linux-scsi@vger.kernel.org Cc: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, I have a basic query related to the Scsi_Host_Template fields namely : cmd_per_lun and can_queue. I would like to know what is the relation between the per-lun queue and the per-HBA queue ? To elaborate my query, I would like to know how are the I/Os from the upper-layers managed between per-lun and the host-queue depth. In most cases the host-queue depth is very large [128 or more], while the per-lun queue is a fraction [5 or 2]. I would like to know how is the relation between the two queues and how does this impact io-rate ? - Kindly let me know as I have a blurred picture of the role of the 2 queues. - Thank you very much - Shobhit Mathur __________________________________ Do you Yahoo!? Yahoo! Mail - 50x more storage than other providers! http://promotions.yahoo.com/new_mail