Hi folks, I think I've found the problem. At least there are a couple of problems here. 1. When the md code tries to run the various hot-add scripts, it gives back a fairly useless error. It should instead tell you that the device is locked by some other user and hopefully tell you WHAT that user is. I finally started poking around at device mapper stuff as well, and I ran the command: # dmsetup status sdb3: 0 33061770 linear sdb2: 0 1992060 linear data_vg-local_lv: 0 62914560 linear data_vg-local_lv: 62914560 10485760 linear sdb1: 0 497952 linear data_vg-home_lv: 0 83886080 linear data_vg-home_lv: 83886080 23068672 linear sdc2: 0 97656048 linear sdc1: 0 117186993 linear hdg1: 0 234436482 linear Notice how hdg1 is listed as a LINEAR device. I certainly didn't do that by default, god knows how it gets picked up. But once I did: # dmsetup remove hdg1 It was removed!! # dmsetup status sdb3: 0 33061770 linear sdb2: 0 1992060 linear data_vg-local_lv: 0 62914560 linear data_vg-local_lv: 62914560 10485760 linear sdb1: 0 497952 linear data_vg-home_lv: 0 83886080 linear data_vg-home_lv: 83886080 23068672 linear sdc2: 0 97656048 linear sdc1: 0 117186993 linear So now I was able to do: # mdadm /dev/md0 --force -a /dev/hdg1 mdadm: hot added /dev/hdg1 Which was great to see. # cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid5] md0 : active raid1 hdg1[2] hde1[0] 117218176 blocks [2/1] [U_] [>....................] recovery = 0.5% (673664/117218176) finish=49.0min speed=39627K/sec unused devices: <none> And now it's re-building the mirror properly. So now I need to see how I can stop the Device Mapper stuff from taking over and controlling various devices. The /dev/sdb? and the /dev/sdc? ones are also problematic, since those are just a second SCSI disk and a USB storage device. Hmm... I wonder if I remove the usb-storage device from device mapper I'll be able to finally write all the data to it without locking up the system. Gotta try that out. I do appreciate the people who gave suggestions, even though it didn't turn out to be the right solution in the end. Now to figure out how to make device mapper only look at /dev/md* devices in the future. John - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
