On 01/14/2015 11:05 AM, Bart Van Assche wrote: > The LIO and SCST SCSI target subsystems consist of the following components: > * A core that processes SCSI commands and that provides common > functionality like persistent reservations, LUN masking and an interface > that allows configuration from user space. > * Device handlers that allow this core to access SCSI devices, block > devices and files uniformly as SCSI devices. > * Target drivers that implement a storage protocol (iSCSI, FC, SRP, > iSER, FCoE, ...) and that realize the SCSI request and response > communication between the target system and an initiator system. > > A significant amount of code is shared between several LIO target > drivers and the SCST target drivers that implement the same storage > protocol. Since there are two sets of these drivers this means that each > set has to be maintained, extended and tested separately. This means a > lot of redundant work. The main difference between these two sets of > drivers is the interface between the target drivers and the SCSI target > core. Hence the proposal to discuss the unification of the API between > SCSI target core and SCSI target drivers. Implementing a single unified > API would have the following advantages: > * A single set of target drivers works for both projects which means a > reduction of the maintenance effort for those who maintain target > drivers for target driver developers and target driver users. > * This would increase the size of the user base for the unified target > drivers. > * This would reduce the workload for the storage target maintainers. > * This would motivate the SCST target driver maintainers to contribute > to the upstream target drivers and to bring the upstream SRP and FCoE > target drivers to the same feature and stability level as their SCST > counterparts. In other words, the LIO users would also benefit from this > work. > * This effort would also help SCST users by ensuring that all latest > target driver features are also available to SCST users. Some time ago > (but no longer today) the LIO QLogic target driver was ahead of the SCST > QLogic target driver. This motivated an SCST user to port the LIO QLogic > target driver to SCST. See also Greg Wettstein, New release of > SCST/Qlogic target interface driver, linux-scsi, April 2014, > http://marc.info/?l=linux-scsi&m=139649571807085). > > During the first phase of this initiative the focus will be on the > QLogic FC, SRP and FCoE target drivers since a significant part of the > code of these drivers is shared between the two target frameworks. > > For those who are not following the SCST project: I'm maintaining the > SCST SRP and FCoE target drivers. > > Nic, in case it was not yet clear, you would be more than welcome during > this session :-) > I'd like to have this discussion, too. It would be really good if we can make that work; after all, Linux should be about _choice_. So if both parties agree to have this discussion I'm all for it. I can even act as a moderator if required :-) 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
