On 06/23/2015 10:29 AM, Nicholas A. Bellinger wrote: > On Fri, 2015-06-19 at 09:13 +0200, Hannes Reinecke wrote: >> On 06/19/2015 08:48 AM, Christoph Hellwig wrote: >>> What's the benefit of the SAS transport class writeout? I honestly >>> always saw tcm_loop as a simple loopback driver, with the different >>> transport IDs in the PR code as a gimmick. Note that vhost and >>> xen-blkback copies that style and I did plan to consolidate it >>> in common code. >>> >> The benefit is that tcm_loop will show up in the system as a 'real' >> SAS hba; long-term goal is to simulate SAS multipathing here. >> I was even planning on adding simlated FC infrastructure, too; >> with that we could simulate FC multipathing, too, and our QA would >> be _so_ happy... >> > > Sounds like a reasonable use-case to support for loopback testing. > >> Again, these patches are mainly a collection of patches I've done to >> test various scenarios, in the hope others might find them useful, >> too. So I can easily hold off these patches until you've posted your >> rework. >> > > How different do you expect sas, fc, and iscsi transports to be..? > > Do you think this would this be better served by a simple tcm_loop LLD > specific API for different multipath transports..? > Actually, I would split off the various transport functions into separate files (tcm_loop_sas, tcm_loop_fc, etc), but keep a common tcm_loop module. We can even make transport classes optional by adding an explicit 'sas.XXX' prefix scanning when creating the device similar to what we do with the 'fc.XXX' prefix already. With that we would have a 'sas.XXX', 'fc.XXX', and 'iqn.XXX' WWN which would attach to the respective transport class, and any other WWN (which would be the default) would be getting the standard emulation without any transport class attached. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
