On 1/14/15, 2:05 AM, "Bart Van Assche" <bart.vanassche@xxxxxxxxxxx> 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 :-) > >Bart. QT> +1. This would be a plus for Qlogic to have 2 stacks under a unify API. Test resource & devlopment cycles are limited. A lot of cycles are loss in keeping patches in sync. Would like to listen in at LSF to hear the discussion.
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