• Apollon Oikonomopoulos's avatar
    Pause DRBD sync for OS install if not wait_for_sync · 41e1e79e
    Apollon Oikonomopoulos authored
    
    
    When wait_for_sync is set to False in LUInstanceCreate, Ganeti lets DRBD sync
    in the background while performing the rest of the installation steps,
    including OS installation.
    
    However, OS installation is a very disk-intensive task that intereferes badly
    with the background I/O caused by DRBD's initial sync. To this end, we pause
    the background sync before OS installation and unpause it afterwards, which
    yields a significant speed boost for OS installation. The following should be
    noted:
    
    a) The user has requested not to wait for sync, i.e. the instance will be
       non-redundant for an unspecified interval anyway and delaying this by a
       couple of minutes is not a big compromise.
    
    b) This approach is also followed during disk wiping.
    Signed-off-by: default avatarApollon Oikonomopoulos <apollon@noc.grnet.gr>
    [iustin@google.com: simplify an if check]
    Signed-off-by: default avatarIustin Pop <iustin@google.com>
    Reviewed-by: default avatarIustin Pop <iustin@google.com>
    41e1e79e
cmdlib.py 468 KB