• NeilBrown's avatar
    md: create externally visible flags for supporting hot-replace. · 2d78f8c4
    NeilBrown authored
    hot-replace is a feature being added to md which will allow a
    device to be replaced without removing it from the array first.
    With hot-replace a spare can be activated and recovery can start while
    the original device is still in place, thus allowing a transition from
    an unreliable device to a reliable device without leaving the array
    degraded during the transition.  It can also be use when the original
    device is still reliable but it not wanted for some reason.
    This will eventually be supported in RAID4/5/6 and RAID10.
    This patch adds a super-block flag to distinguish the replacement
    device.  If an old kernel sees this flag it will reject the device.
    It also adds two per-device flags which are viewable and settable via
       "want_replacement" can be set to request that a device be replaced.
       "replacement" is set to show that this device is replacing another
    The "rd%d" links in /sys/block/mdXx/md only apply to the original
    device, not the replacement.  We currently don't make links for the
    replacement - there doesn't seem to be a need.
    Signed-off-by: default avatarNeilBrown <neilb@suse.de>
md.txt 25.4 KB