Hi Mike, On Mon, 4 Jun 2018 12:13:22 -0500, Mike Christie wrote: > On 06/03/2018 07:57 AM, David Disseldorp wrote: ... > > I considered more granular toggles, but decided against it due to the > > added configuration/implementation complexity. Happy to revisit this if > > others would prefer it though. > > I might not understand your original "enforce" part of the patch > description, because it seems like you must do this. I've changed "enforce" to "ensure". > I think ATS only is the default for the newer versions of ESX when the > device reports it supports ATS, and it seems like running windows > clustering in VMs on ESX is common. So, you will have that combo of ATS > only with PRs a lot. I don't think a combination of SCSI2 and persistent reservations is common, as VMware recommends Raw Device Mapping (via a separate LUN) for most Windows Failover Cluster use use cases[1]. See: https://docs.vmware.com/en/VMware-vSphere/6.5/vsphere-esxi-vcenter-server-651-setup-mscs.pdf IMO a single toggle to disable both RESERVE / RELEASE and Persistent Reservation handling for a given backstore is still the simplest and most user friendly option here. > When you wrote "enforce" earlier I thought you meant the patch is > supposed to make sure that ATS only is really on and if ESX messes up > (or maybe the user messed up the settings) and it sends a > RESERVE/RELEASE then it is failed. I do not see how that is possible > with your patch with something like windows clustering VMs. > > If the patch was more for protecting against the case where the backend > does not support reservations, and ATS only was used to make sure they > are never used due to that, and we assume backends always implement > older reservations if they implement newer PRs then I think the patch is > fine. > > So I do not really care :) I think it depends on what you were trying to > support. Some older versions of ESX/VMFS can fall back to using SCSI2 reservations instead of ATS[2]. Disabling LIO SCSI2+PR support restricts this fallback behaviour. That's what I was trying to get across in the commit message :) New version to follow... Cheers, David 1) Windows Failover Cluster on VMware https://docs.vmware.com/en/VMware-vSphere/6.5/vsphere-esxi-vcenter-server-651-setup-mscs.pdf 2) vSphere 5 SCSI reservations vs ATS locking https://pubs.vmware.com/vsphere-50/topic/com.vmware.vsphere.storage.doc_50/GUID-DE30AAE3-72ED-43BF-95B3-A2B885A713DB.html -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
