From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Anderson Subject: Re: [RFC]: 64 bit LUN/Tags, dummy device in host_queue, host_lock <-> LLDD reentrancy Date: Mon, 26 Aug 2002 10:27:46 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20020826172746.GA1301@beaverton.ibm.com> References: <200208261648.g7QGm6b00427@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200208261648.g7QGm6b00427@localhost.localdomain> List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Aron Zeh , Luben Tuikov , linux-scsi James Bottomley [James.Bottomley@SteelEye.com] wrote: > ARZEH@de.ibm.com said: > > Does the use of driverfs-names mean that the HBA driver somehow comes > > into the discovery-loop for devices (e.g. scan_scsis somehow interacts > > with the HBA driver to determine which driverfs entry to create.)? > > Well, scanning is really only for legacy. Way into the future, I'd like to > see hotplug notification for device attach events, so no fibre controller ever > need be troubled by the scan. All they'd do is send a device attach > notification into SCSI when they detect one. (SCSI would probably then turn > around and ask for a REPORT_LUNS). > There will probably still need to be some form of scan through the hotplug scripts based on a HAs capability (parallel SCSI, FC loop). A CAM-3 like indication that the HA is capable of auto discovery or needs a probe from min-max. > > Shouldn't there be some sort of rule for LUN (or unit) naming within > > at least the same hardware class? That is for: parallel, iSCSI, FC, > > etc. Will the SCSI stack automatically try to discover all devices > > behind the HBA (e.g, on the FC SAN)? Or will there be an interface to > > restrict the range, etc? > > Yes, there should. But such a rule would only be for maintaining consistency > within driverfs, and therefore could happily become Patric Mochel's problem. > If we go the whole hotplug route, discovery would be up to the scsi hotplug > scripts. > > > Lastly, how will you keep track of LUNs in the SCSI stack? Will the > > current LUN field disappear in favour of a generic character string? > > Internally to Scsi_Device, LUNs will be linked by pointers. How we know > whether such a linkage needs to occur, I'm not yet sure about. In the worst > case we could use driverfs matching to see if a newly discovered device's PUN > matches an existing device, or there might be a way for the HBA driver to > supply the information. > James I do not follow the usage of LUNs linked by pointers, can you explain further? -Mike -- Michael Anderson andmike@us.ibm.com