James Bottomley wrote: > On Thu, 2006-06-08 at 14:13 -0500, Michael Reed wrote: >> I created an md device on two fibre channel disks, sde and sdf. >> I then disabled the switch port to which the hba is connected. >> After the remote port time out messages, I re-enabled the switch >> port. Three things happen that are weird. First, two unexpected >> responses while scanning. Second, the creation of sdm and >> sdn. Third, the md device remains inaccessible. > > This is sort of as expected. What you did was wait out the reconnection > timer, so the mid layer failed and offlined the devices. Thus, when > they come back, they get new instances. If you'd done a remove-device > after they went offline, they'd have come back to the same location (as > long as nothing had them open). But this is user level stuff. In this instance, there was no i/o in progress so the mid-layer didn't take the device off line. It was simply removed by the transport. > Basically, when a path goes dead it's up to the multi-path user level to > remove it an wait for udev to inform it that another SCSI node has > appeared and has the correct signature to be another path to the device. Are there notification mechanisms in place such that a driver which has the device opened (claimed?) will be notified upon it's removal? Should there be? Could it happen via a driver callback? Udev? Both? I like the idea of a callback so that the removal has a chance of being complete. Is it possible to do a better job of reconnecting a removed target to an open sd? Thanks, Mike > >> I don't think this is working the way it's intended to. I >> suspect it will cause big problems for multi-path volume managers >> in a fail back situation. > > James > > - : 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
