From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [LSF/MM TOPIC] Target fabric module for SCSI para-virtualization Date: Mon, 07 Feb 2011 09:07:49 +0100 Message-ID: <4D4FA855.2030904@suse.de> References: <1297065435.13752.173.camel@haakon2.linux-iscsi.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor.suse.de ([195.135.220.2]:38279 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752708Ab1BGH7k (ORCPT ); Mon, 7 Feb 2011 02:59:40 -0500 In-Reply-To: <1297065435.13752.173.camel@haakon2.linux-iscsi.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-iscsi-target-dev@googlegroups.com Cc: "Nicholas A. Bellinger" , lsf-pc@lists.linuxfoundation.org, linux-scsi , Stefan Hajnoczi , Anthony Liguori , Christoph Hellwig On 02/07/2011 08:57 AM, Nicholas A. Bellinger wrote: > Greetings all, >=20 > [Topic] >=20 > A hybrid target fabric module for QEMU/KVM SCSI para-virtualization >=20 > [Abstract] >=20 > Currently we use the TCM_Loop v4 fabric module with mainline .38 targ= et > code to present SCSI LUNs with high level multi-fabric (iSCSI, FC, SA= S) > SPC-3 port WWN emulation into KVM guests using two different forms of > QEMU HBA hardware emulation. However both of these currently require > interaction with the QEMU block layer and extra overhead of OS > independent code running in user-space connected to our existing > SG_IO/BSG interfaces. This also has the limitiation that we currentl= y > cannot perform explict SCSI Initiator Port access management for LUNs > also present via TCM_Loop SCSI LLD driver on the KVM host. >=20 > Recently there has been an off-list discussion between myself and > members of the QEMU/KVM community, and they have expressed an interes= t > in seeing a native paravirtualized SCSI passthrough available to QEMU > guests with direct interaction into TCM fabric module code running on > KVM host. This would be using existing CDB level port emulation code= in > target_core_fabric_lib.c, and (mostly) generic fabric control plane i= n > target_core_fabric_configfs.c.. Beyond the TCM fabric module specifi= cs, > this will require: >=20 > *) An asynchronous I/O capable virtio interface for KVM that does not > require direct QEMU block-layer interaction >=20 > *) A multi-fabric WWN naming capable TCM fabric module using native > virtio-scsi connections to individual KVM guests for kernel-level > passthrough into TCM backend storage. (eg: similar to TCM_Loop, but = w/o > the Linux/SCSI LLD frontend, and full explict Initiator port NodeACL = + > MappedLUN control abstraction) >=20 > *) Guest OS specific para-virtualized SCSI driver packages (similar t= o > virtio-blk) performing SCSI I/O handoff into passthrough interface vi= a > SCSI I_T nexues, with proper T10 WWN Port and LUN naming provided fro= m > underlying TCM v4.x infrastructure (eg: full compat w/ existing SPC-= 3 > capable cluster clients) >=20 YES! One item less on my long-term to-do list. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html