openstack team mailing list archive

[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

I did some cleanup of stop and power_off in the review here.

https://review.openstack.org/#/c/8021/

I removed the weird  shutdown_terminate handling. Honestly I feel like
that is compatibility we don't need. It should be up to the provider whether
a stop_instances counts as a terminate. In my mind they are two different things.

Comments welcome on the review.

Vish

On May 31, 2012, at 6:40 PM, Yun Mao wrote:

> shutdown, stop, are power_off are synonym in this discussion. They all
> mean to stop the VM from running, but keep the disk image and network,
> so that the VM could be started back on again.
> 
> There are three ways to do it: 1) using EC2 stop-instance API. 2) use
> OS API stop-server. 3) inside the VM, execute halt or equivalent.
> However, the devil is in the details.
> 
> In EC2 API, a shutdown_terminate flag is checked when a stop-instance
> call is issued. If it's true, then stop-instances actually means
> terminate instances. The flag is true by default unless there is block
> device mapping provided, and it doesn't appear to be configurable by a
> user.
> 
> In OS API, it's defined in v1.1, neither the specification nor the
> implementation check the shutdown_terminate flag at all. It will
> always do stop instead of terminate.
> 
> So, when shutdown_terminate is true (default), the OS API and the EC2
> API will behave differently. If we accept this, it might still be
> acceptable. After all they are different APIs and could have different
> behavior. But the pickle is the case where a user initiates a shutdown
> inside the VM. What's the expected behavior after it's detected?
> Should it respect the shutdown_terminate flag or work more like an OS
> API?  Right now when a shutdown in a VM is detected, the vm state is
> updated to SHUTOFF and that's pretty much it..
> 
> To summarize, there are 3 ways of doing the same thing, each now has a
> different behavior. I'd vote to patch the code to be a little more
> consistent. But what should be the right behavior?
> 
> Yun
> 
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