• Goldwyn Rodrigues's avatar
    Add new disk to clustered array · 1aee41f6
    Goldwyn Rodrigues authored
    Algorithm:
    1. Node 1 issues mdadm --manage /dev/mdX --add /dev/sdYY which issues
       ioctl(ADD_NEW_DISC with disc.state set to MD_DISK_CLUSTER_ADD)
    2. Node 1 sends NEWDISK with uuid and slot number
    3. Other nodes issue kobject_uevent_env with uuid and slot number
    (Steps 4,5 could be a udev rule)
    4. In userspace, the node searches for the disk, perhaps
       using blkid -t SUB_UUID=""
    5. Other nodes issue either of the following depending on whether the disk
       was found:
       ioctl(ADD_NEW_DISK with disc.state set to MD_DISK_CANDIDATE and
    	 disc.number set to slot number)
       ioctl(CLUSTERED_DISK_NACK)
    6. Other nodes drop lock on no-new-devs (CR) if device is found
    7. Node 1 attempts EX lock on no-new-devs
    8. If node 1 gets the lock, it sends METADATA_UPDATED after unmarking the disk
       as SpareLocal
    9. If not (get no-new-dev lock), it fails the operation and sends METADATA_UPDATED
    10. Other nodes understand if the device is added or not by reading the superblock again after receiving the METADATA_UPDATED message.
    Signed-off-by: default avatarLidong Zhong <lzhong@suse.com>
    Signed-off-by: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
    1aee41f6
md_p.h 11.9 KB