On Wed, 2008-10-22 at 21:54 +0200, Christophe Varoqui wrote: > It seems to me the device handler infrastructure proposes to translate > scsi error codes from requests generated by the device handler itself. I No, the handler doesn't generate the requests. Device handler's check_sense() function is called from the scsi_error.c:scsi_check_sense() function whenever a sense code is returned from the device (on normal I/Os). When in the sense function, the device handler can do any action (like closing the other path(s)) and returning an appropriate error code (such that dm doesn't retry the I/O on other paths). > don't know how we can detect a reservation conflict from a device > handler without submitting a dangerous write io. > > I don't see how we could use a device handler to translate an scsi error > code from a write io submitted to the multipath device map. Do you ? That is what it actually does, it intercepts the sense code returned from the device on normal I/Os. > > Regards, > cvaroqui > > > > The SCSI Hardware handler is created for devices with special needs. > > It is available in 2.6.27. One can be written for any device to > > translate the scsi sense code to a different error code that the dm > > understands. Is this something that coule help this situation ? > > > > Have a look at drivers/scsi/device_handler directory. > > > > Hope this helps, > > > > chandra > > On Tue, 2008-10-21 at 23:19 +0200, Christophe Varoqui wrote: > > > Hi, > > > > > > the dm-mpath multipathing driver enqueues write ios returned by > > > the scsi layer with a "reservation conflict" error (on assymetric > > > storage controllers, like Clariion, where queue_if_no_path is > > > enabled). > > > > > > This is wrong, and a potent data-corrupter : wio sent to a reserved > > > scsi device should never be retried on this same device. > > > > > > Can someone advise on a viable solution for this problem ? I > > > understand the Device Mapper being a block remapper, it is not > > > expected to receive scsi errors directly ... but maybe some kind of > > > translation might be acceptable. Or is there hope in the > > > request-based remapper ? > > > > > > Jens, James, Alasdair, ... as maintainers of the involved > > > subsystems, would you care to give some advise on the issue. > > > > > > > -- > To unsubscribe from this list: 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 -- To unsubscribe from this list: 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
