On Oct 1 09:20, Keith Busch wrote: > On Thu, Oct 01, 2020 at 06:10:57AM +0200, Klaus Jensen wrote: > > On Sep 30 15:04, Keith Busch wrote: > > > Let the user specify a specific namespace if they want to get access > > > stats for a specific namespace. > > > > > > > I don't think this makes sense for v1.3+. > > > > NVM Express v1.3d, Section 5.14.1.2: "There is no namespace specific > > information defined in the SMART / Health log page in this revision of > > the specification. therefore the controller log page and namespace > > specific log page contain identical information". > > > > I have no idea why the TWG decided this, but that's the way it is ;) > > I don't think they did that. The behavior you're referring to is specific to > controllers that operate a particular way: "If the log page is not supported > on > a per namespace basis ...". They were trying to provide a spec compliant way > for controllers to return a success status if you supplied a valid NSID when > the controller doesn't support per-namespace smart data.. > > The previous paragraph is more clear on this: "The controller may also support > requesting the log page on a per namespace basis, as indicated by bit 0 of the > LPA field in the Identify Controller data structure".
OK, so I agree that it makes sense for it to be supported on a per namespace basis, but I think the spec is just keeping the door open for future namespace specific stuff in the log page - currently there is none. Figure 94 (the actual SMART log page) says that the Data Units Read/Written are controller wide, so there really is no namespace specific information. Maybe this could be in the context of shared namespaces? How would a controller know how much data has been read/written from it without asking the other controllers? What if a controller is detached from the namespace - you'd lose those numbers.
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