• Neil Brown's avatar
    [PATCH] Provide a 'safe-mode' for soft raid. · 063e9f83
    Neil Brown authored
    When a raid1 or raid5 array is in 'safe-mode', then the array
    is marked clean whenever there are no outstanding write requests,
    and is marked dirty again before allowing any write request to
    proceed.
    
    This means than an unclean shutdown while no write activity is happening
    will NOT cause a resync to be required.  However it does mean extra
    updates to the superblock.
    
    Currently safe-mode is turned on by sending SIGKILL to the raid thread
    as would happen at a normal shutdown.  This should mean that the
    reboot notifier is no longer needed.
    
    After looking more at performance issues I may make safemode be on
    all the time.  I will almost certainly make it on when RAID5 is degraded
    as an unclean shutdown of a degraded RAID5 means data loss.
    
    This code was provided by  Angus Sawyer <angus.sawyer@dsl.pipex.com>
    063e9f83
raid5.c 45.8 KB