This is something I am not aware of, thanks! In this case, do I have to worry about cases where the new drive might not be able to boot (this is raid1 with 2 drives, and both drives need to be able to boot up the server by themselves in case the other drive fails later)? I remember I had to do the following before for the new drive: grub> root (hd0,0) Is that still the case here if marking it as 'spare'? On Dec 8, 2013, at 4:53 PM, NeilBrown <neilb@xxxxxxx> wrote: > On Sun, 8 Dec 2013 16:45:08 -0600 hai wu <haiwu.us@xxxxxxxxx> wrote: > >> Thanks Neil. I am not sure if I understand mdadm 'spare' correctly. If >> doing as you mentioned above, the new driver will show up in output of >> "mdadm --detail /dev/md0" as 'spare' status, while I would like the new >> drive to automatically show up as "acitve, sync", and it will automatically >> be synced up with the one remaining good drive upon running the udev rule. >> I don't see an option like "force-include" in this case. Please let me know >> if I miss something. > > Whenever md notices that an array has a spare device and a missing device it > will start rebuilding the spare and will then make it an active device. > > So if a new device is added to the system, you really do want to give it to > md as a 'spare'. md will do the rest - it always has done. > > NeilBrown > > >> >> >> On Sun, Dec 8, 2013 at 3:55 PM, NeilBrown <neilb@xxxxxxx> wrote: >> >>> On Sun, 8 Dec 2013 11:53:00 -0600 Hai Wu <haiwu.us@xxxxxxxxx> wrote: >>> >>>> I am wondering whether it is possible for mdadm to auto-rebuild a failed >>>> raid1 driver upon its replacement with a new drive? The following lines >>>> from some RedHat website URL seems to indicate vaguely that it might be >>> possible: >>>> >>> >>> Yes and no. >>> "yes" because it is certainly possible to arrange this, >>> "no" because it isn't just mdadm which does it. >>> >>> When a drive is plugged in, udev notices and can run various commands to do >>> things with that device. You need to get udev to run "mdadm -I $devname" >>> when a new device is plugged in. >>> The udev scripts which come with mdadm will only do that for new drives >>> which >>> appear to be part of an array already. You presumably want it to do that >>> for >>> any new drive. The change should be quite easy. >>> >>> Secondly, you need to tell mdadm that it is OK to add a new device as a >>> spare >>> to an array. To see how to do this you need to read the documentation for >>> the "POLICY" command in mdadm.conf.5. >>> >>> A line like: >>> POLICY action=force-spare >>> tells mdadm that any device passed to "mdadm -I" can be added to any array >>> as >>> a spare. You might not want that, but you can restrict it in various ways. >>> >>> POLICY path=pci-0000:00:1f.2-scsi* action=spare >>> >>> says that any device attached to a particular controller can be added to >>> any >>> array as long as it is already a member of the array, or appears to be >>> blank. >>> >>> There are various other directives which should allow you to describe >>> whatever you want. >>> >>> NeilBrown >>> >>> >>>> Previously, mdadm was not able to rebuild newly-connected drives >>>> automatically. This update adds the array auto-rebuild feature and >>> allows a >>>> RAID stack to automatically rebuild newly-connected drives. >>>> >>>> The goal is to get mdadm software raid1 to behave the same as hardware >>>> raid1, when replacing failed hard drive. It should automatically detect >>> new >>>> drive and rebuild the new drive into part of raid1 ..-- >>>> 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 >>> >>> > -- 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
