On Thu, Oct 03, 2013 at 11:44:46AM -0500, Alex Ough wrote: > I'm not sure what else commands 'MigrateCommand' actually execute in > addition to 'Start/Stop/CopyCommand', but can we include 'MigrateCommand' > if it consists of only those 3 commands? > > Thanks > Alex Ough
In the case of VMware, the migrate command is executed via the MigrateVMTask that's part of the VMware SDK (see vmware-base/src/com/cloud/hypervisor/vmware/mo/VirtualMachineMO.java). For VMware, I know that vCenter will queue and process concurrent requests for migrations. Specifically, it will throttle the migrations happening, based on it's internal concurrency constraints, but the task queue will still accept more connections. Obviously the risk are the VMware layer tasks timing out if it takes too long for the task queue to complete. As for XenServer, it's happening in what appears to be a similar way (although the source host is the target for the migration API call). Check plugins/hypervisors/xen/src/com/cloud/hypervisor/xen/resource/CitrixResourceBase.java. I'm not familiar enough with XenServer's concurrency model for migrations. Any experts know the answer to if it can handle concurrency in a stable way? With KVM, it's obviously executing via the agent. Similarly to XenServer, I'm not familiar enough to know about concurrent operations. So do the HV experts on the list have any opinions about XenServer and KVM migration concurrency? -chip
