Hi James:
 
    I found another issue during test.
    When migrating VM from host A to B, it contains following process.
    1) memory copy
    2) suspend VM on A
    3) transfer some other thing to B such as tsc state.
 
    If step (3) failed,  VM will be resumed on host A.
    Well, from the test of view,  the resume cannot be completed successfully.
 
    Out test is migrating 12VMs between twn host over again and again.
    The attached log doing exactly below things
    1) Migrate from Host B, so fisrt resuming (line 25 to 474)
    2) Later want to migrating to B again, so suspending (line 474 to line 1116)
    3) Migrating failed and enter into resuming again  (line 1118 to line 1399). 
 
     line 1383 is waiting vbd state to be changed but can not get the response.
And 1392 show a "Unacknowledged event word ". From the log, it looks like
this is due to XenVbd_HwScsiResetBus in line 1397.
 
      Question is what trigger the XenVbd_HwScsiResetBus during resuming?
 
       Thanks.