Hi all,
        I have an ovirt4.2 environment of 3 hosts. Now all vms in this environment could not be migrated. But all the vms could be started on all 3 hosts. Anyone can help? Thanks a lot!

engine logs:

2019-01-02 09:41:26,868+08 INFO  [org.ovirt.engine.core.bll.MigrateVmCommand] (default task-9) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] Lock Acquired to object 'EngineLock:{exclusiveLocks='[eff7f697-8a07-46e5-a631-a1011a0eb836=VM]', sharedLocks=''}'
2019-01-02 09:41:26,978+08 INFO  [org.ovirt.engine.core.bll.MigrateVmCommand] (EE-ManagedThreadFactory-engine-Thread-168938) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] Running command: MigrateVmCommand internal: false. Entities affected :  ID: eff7f697-8a07-46e5-a631-a1011a0eb836 Type: VMAction group MIGRATE_VM with role type USER
2019-01-02 09:41:27,019+08 INFO  [org.ovirt.engine.core.vdsbroker.MigrateVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168938) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] START, MigrateVDSCommand( MigrateVDSCommandParameters:{hostId='0aff0075-4b41-4f37-98de-7433a17cd47e', vmId='eff7f697-8a07-46e5-a631-a1011a0eb836', srcHost='horeb66', dstVdsId='5bb18f6e-9c7e-4afd-92de-f6482bf752e5', dstHost='horeb65:54321', migrationMethod='ONLINE', tunnelMigration='false', migrationDowntime='0', autoConverge='true', migrateCompressed='false', consoleAddress='null', maxBandwidth='500', enableGuestEvents='true', maxIncomingMigrations='2', maxOutgoingMigrations='2', convergenceSchedule='[init=[{name=setDowntime, params=[100]}], stalling=[{limit=1, action={name=setDowntime, params=[150]}}, {limit=2, action={name=setDowntime, params=[200]}}, {limit=3, action={name=setDowntime, params=[300]}}, {limit=4, action={name=setDowntime, params=[400]}}, {limit=6, action={name=setDowntime, params=[500]}}, {limit=-1, action={name=abort, params=[]}}]]', dstQemu='192.168.128.78'}), log id: 1bd72db2
2019-01-02 09:41:27,019+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateBrokerVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168938) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] START, MigrateBrokerVDSCommand(HostName = horeb66, MigrateVDSCommandParameters:{hostId='0aff0075-4b41-4f37-98de-7433a17cd47e', vmId='eff7f697-8a07-46e5-a631-a1011a0eb836', srcHost='horeb66', dstVdsId='5bb18f6e-9c7e-4afd-92de-f6482bf752e5', dstHost='horeb65:54321', migrationMethod='ONLINE', tunnelMigration='false', migrationDowntime='0', autoConverge='true', migrateCompressed='false', consoleAddress='null', maxBandwidth='500', enableGuestEvents='true', maxIncomingMigrations='2', maxOutgoingMigrations='2', convergenceSchedule='[init=[{name=setDowntime, params=[100]}], stalling=[{limit=1, action={name=setDowntime, params=[150]}}, {limit=2, action={name=setDowntime, params=[200]}}, {limit=3, action={name=setDowntime, params=[300]}}, {limit=4, action={name=setDowntime, params=[400]}}, {limit=6, action={name=setDowntime, params=[500]}}, {limit=-1, action={name=abort, params=[]}}]]', dstQemu='192.168.128.78'}), log id: 380b8d38
2019-01-02 09:41:27,025+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateBrokerVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168938) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] FINISH, MigrateBrokerVDSCommand, log id: 380b8d38
2019-01-02 09:41:27,029+08 INFO  [org.ovirt.engine.core.vdsbroker.MigrateVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168938) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] FINISH, MigrateVDSCommand, return: MigratingFrom, log id: 1bd72db2
2019-01-02 09:41:27,036+08 INFO  [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-168938) [3eed5f0e-aaf5-4dce-bf30-2c49e09ab30d] EVENT_ID: VM_MIGRATION_START(62), Migration started (VM: win7, Source: horeb66, Destination: horeb65, User: admin@internal-authz). 
2019-01-02 09:41:41,557+08 INFO  [org.ovirt.engine.core.vdsbroker.monitoring.VmAnalyzer] (EE-ManagedThreadFactory-engineScheduled-Thread-30) [] VM 'eff7f697-8a07-46e5-a631-a1011a0eb836'(win7) moved from 'MigratingFrom' --> 'Up'
2019-01-02 09:41:41,557+08 INFO  [org.ovirt.engine.core.vdsbroker.monitoring.VmAnalyzer] (EE-ManagedThreadFactory-engineScheduled-Thread-30) [] Adding VM 'eff7f697-8a07-46e5-a631-a1011a0eb836'(win7) to re-run list
2019-01-02 09:41:41,567+08 ERROR [org.ovirt.engine.core.vdsbroker.monitoring.VmsMonitoring] (EE-ManagedThreadFactory-engineScheduled-Thread-30) [] Rerun VM 'eff7f697-8a07-46e5-a631-a1011a0eb836'. Called from VDS 'horeb66'
2019-01-02 09:41:41,570+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateStatusVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] START, MigrateStatusVDSCommand(HostName = horeb66, MigrateStatusVDSCommandParameters:{hostId='0aff0075-4b41-4f37-98de-7433a17cd47e', vmId='eff7f697-8a07-46e5-a631-a1011a0eb836'}), log id: 4ed2923c
2019-01-02 09:41:41,573+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateStatusVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] FINISH, MigrateStatusVDSCommand, log id: 4ed2923c
2019-01-02 09:41:41,583+08 WARN  [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-168945) [] EVENT_ID: VM_MIGRATION_TRYING_RERUN(128), Failed to migrate VM win7 to Host horeb65 . Trying to migrate to another Host.
2019-01-02 09:41:41,642+08 INFO  [org.ovirt.engine.core.bll.MigrateVmCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] Running command: MigrateVmCommand internal: false. Entities affected :  ID: eff7f697-8a07-46e5-a631-a1011a0eb836 Type: VMAction group MIGRATE_VM with role type USER
2019-01-02 09:41:41,671+08 INFO  [org.ovirt.engine.core.vdsbroker.MigrateVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] START, MigrateVDSCommand( MigrateVDSCommandParameters:{hostId='0aff0075-4b41-4f37-98de-7433a17cd47e', vmId='eff7f697-8a07-46e5-a631-a1011a0eb836', srcHost='horeb66', dstVdsId='20786f47-87fe-4ef6-be82-b580e5d0a350', dstHost='horeb67:54321', migrationMethod='ONLINE', tunnelMigration='false', migrationDowntime='0', autoConverge='true', migrateCompressed='false', consoleAddress='null', maxBandwidth='500', enableGuestEvents='true', maxIncomingMigrations='2', maxOutgoingMigrations='2', convergenceSchedule='[init=[{name=setDowntime, params=[100]}], stalling=[{limit=1, action={name=setDowntime, params=[150]}}, {limit=2, action={name=setDowntime, params=[200]}}, {limit=3, action={name=setDowntime, params=[300]}}, {limit=4, action={name=setDowntime, params=[400]}}, {limit=6, action={name=setDowntime, params=[500]}}, {limit=-1, action={name=abort, params=[]}}]]', dstQemu='192.168.128.76'}), log id: 4611863
2019-01-02 09:41:41,672+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateBrokerVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] START, MigrateBrokerVDSCommand(HostName = horeb66, MigrateVDSCommandParameters:{hostId='0aff0075-4b41-4f37-98de-7433a17cd47e', vmId='eff7f697-8a07-46e5-a631-a1011a0eb836', srcHost='horeb66', dstVdsId='20786f47-87fe-4ef6-be82-b580e5d0a350', dstHost='horeb67:54321', migrationMethod='ONLINE', tunnelMigration='false', migrationDowntime='0', autoConverge='true', migrateCompressed='false', consoleAddress='null', maxBandwidth='500', enableGuestEvents='true', maxIncomingMigrations='2', maxOutgoingMigrations='2', convergenceSchedule='[init=[{name=setDowntime, params=[100]}], stalling=[{limit=1, action={name=setDowntime, params=[150]}}, {limit=2, action={name=setDowntime, params=[200]}}, {limit=3, action={name=setDowntime, params=[300]}}, {limit=4, action={name=setDowntime, params=[400]}}, {limit=6, action={name=setDowntime, params=[500]}}, {limit=-1, action={name=abort, params=[]}}]]', dstQemu='192.168.128.76'}), log id: 7d20b357
2019-01-02 09:41:41,677+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateBrokerVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] FINISH, MigrateBrokerVDSCommand, log id: 7d20b357
2019-01-02 09:41:41,682+08 INFO  [org.ovirt.engine.core.vdsbroker.MigrateVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168945) [] FINISH, MigrateVDSCommand, return: MigratingFrom, log id: 4611863
2019-01-02 09:41:41,686+08 INFO  [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-168945) [] EVENT_ID: VM_MIGRATION_START(62), Migration started (VM: win7, Source: horeb66, Destination: horeb67, User: admin@internal-authz). 
2019-01-02 09:41:56,575+08 INFO  [org.ovirt.engine.core.vdsbroker.monitoring.VmAnalyzer] (EE-ManagedThreadFactory-engineScheduled-Thread-45) [] VM 'eff7f697-8a07-46e5-a631-a1011a0eb836'(win7) moved from 'MigratingFrom' --> 'Up'
2019-01-02 09:41:56,575+08 INFO  [org.ovirt.engine.core.vdsbroker.monitoring.VmAnalyzer] (EE-ManagedThreadFactory-engineScheduled-Thread-45) [] Adding VM 'eff7f697-8a07-46e5-a631-a1011a0eb836'(win7) to re-run list
2019-01-02 09:41:56,584+08 ERROR [org.ovirt.engine.core.vdsbroker.monitoring.VmsMonitoring] (EE-ManagedThreadFactory-engineScheduled-Thread-45) [] Rerun VM 'eff7f697-8a07-46e5-a631-a1011a0eb836'. Called from VDS 'horeb66'
2019-01-02 09:41:56,625+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateStatusVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168952) [] START, MigrateStatusVDSCommand(HostName = horeb66, MigrateStatusVDSCommandParameters:{hostId='0aff0075-4b41-4f37-98de-7433a17cd47e', vmId='eff7f697-8a07-46e5-a631-a1011a0eb836'}), log id: 4ded4ce9
2019-01-02 09:41:56,628+08 INFO  [org.ovirt.engine.core.vdsbroker.vdsbroker.MigrateStatusVDSCommand] (EE-ManagedThreadFactory-engine-Thread-168952) [] FINISH, MigrateStatusVDSCommand, log id: 4ded4ce9
2019-01-02 09:41:56,638+08 WARN  [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-168952) [] EVENT_ID: VM_MIGRATION_TRYING_RERUN(128), Failed to migrate VM win7 to Host horeb67 . Trying to migrate to another Host.
2019-01-02 09:41:56,695+08 WARN  [org.ovirt.engine.core.bll.MigrateVmCommand] (EE-ManagedThreadFactory-engine-Thread-168952) [] Validation of action 'MigrateVm' failed for user admin@internal-authz. Reasons: VAR__ACTION__MIGRATE,VAR__TYPE__VM,VAR__ACTION__MIGRATE,VAR__TYPE__VM,VAR__ACTION__MIGRATE,VAR__TYPE__VM,VAR__ACTION__MIGRATE,VAR__TYPE__VM,SCHEDULING_NO_HOSTS
2019-01-02 09:41:56,696+08 INFO  [org.ovirt.engine.core.bll.MigrateVmCommand] (EE-ManagedThreadFactory-engine-Thread-168952) [] Lock freed to object 'EngineLock:{exclusiveLocks='[eff7f697-8a07-46e5-a631-a1011a0eb836=VM]', sharedLocks=''}'
2019-01-02 09:41:56,706+08 WARN  [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-168952) [] EVENT_ID: VM_MIGRATION_NO_VDS_TO_MIGRATE_TO(166), No available host was found to migrate VM win7 to.
2019-01-02 09:41:56,709+08 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engine-Thread-168952) [] EVENT_ID: VM_MIGRATION_FAILED(65), Migration failed  (VM: win7, Source: horeb66).