On Tue, Dec 04 2007, Neil Brown wrote: > > I've been looking at use BIO_RW_FAILFAST in md/raid to improve > handling of some error cases. > > This is particularly significant for the DASD driver (s390 specific). > I believe it uses optic fibre to connect to the drives. When one of > these paths is unplugged, IO requests will block until an operator > runs a command to reset the card (or until it is plugged back in). > The only way to avoid this blockage is to use BIO_RW_FAILFAST. So > we really need BIO_RW_FAILFAST for a reliable RAID1 configuration on > DASD drives. > > However, I just tested BIO_RW_FAILFAST on my SATA drives: controller > > 02:06.0 RAID bus controller: Silicon Image, Inc. SiI 3114 [SATALink/SATARaid] > Serial ATA Controller (rev 02) > > (not using the cards minimal RAID functionality) and requests fail > immediately and always with e.g. > > sd 2:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT > driverbyte=DRIVER_OK,SUGGEST_OK > end_request: I/O error, dev sdc, sector 2048 > > So fail fast obviously isn't generally usable. > > What is the answer here? Is the Silicon Image driver doing the wrong > thing, or is DASD doing the wrong thing, or is BIO_RW_FAILFAST > under-specified and we really need multiple flags or what?
Hrmpf. It looks like the SCSI layer is a little too trigger happy. Any chance you could try and trace where this happens? -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
