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From Marcus Sorensen <shadow...@gmail.com>
Subject Re: A question on vm migrations when hosts are set into a maintenance mode.
Date Wed, 13 Nov 2013 17:18:13 GMT
I'm not sure. I know in the past when I've seen files change locations
it has also clobbered updates to that file. Someone branched, did the
reorganization work, and merged, while in-between the original file
changed.

On Wed, Nov 13, 2013 at 9:21 AM, Alex Ough <alex.ough@sungard.com> wrote:
> All,
>
> While merging my changes to 4.3 branch, I found that the option,
> 'execute.in.sequence.hypervisor.commands' is NOT used in Start/Stop/Copy
> commands in 'VirtualMachineManagerImpl.java' any more as below.
>
>
> *StopCommand stop = new StopCommand(vm, getExecuteInSequence());*
>
> *protected boolean getExecuteInSequence() {*
> *     return false;*
> *}*
>
> As you see in the above, the function, 'getExecuteInSequence', just returns
> false instead of getting the value from the global variable.
>
> And one more change is that the file has been moved to
> 'engine/orchestration/src/com/cloud/vm' from 'server/src/com/cloud/vm'.
>
> Am I missing something related with this or do we stop supporting this
> option in 4.3?
> I'm a little confused, so please help me resolve this.
>
> Thanks
> Alex Ough
>
>
>
>
> On Tue, Nov 12, 2013 at 4:20 PM, Alex Ough <alex.ough@sungard.com> wrote:
>
>> Thanks a lot for your confirmation, Marcus.
>> I'll create a review request unless anyone has an objection.
>>
>> Thanks
>> Alex Ough
>>
>>
>> On Tue, Nov 12, 2013 at 3:37 PM, Marcus Sorensen <shadowsor@gmail.com>wrote:
>>
>>>  I have done parallel KVM migrations without issue, it's "supposed to
>>> work". Really I think it's in the same boat as parallel start/stop. It
>>> should work, but the config option is there just in case. I think we
>>> should add it.
>>>
>>> On Thu, Oct 3, 2013 at 11:41 AM, Chip Childers
>>> <chip.childers@sungard.com> wrote:
>>> > 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
>>> >
>>> >
>>>
>>>
>>

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