On Mon, Apr 20, 2009 at 12:35 PM, Tino Vazquez <tinova@fdi.ucm.es> wrote:

Howdy everyone,

Excellent thread. My three cents:

1) I think we should define clearly the semantics of the states. for
instance, what is the difference between STOPPED and SUSPENDED? Is it
that with SUSPENDED the state is saved and not with STOPPED?

Yes, it's exactly that. From the state registry: STOPPED = "The resource is inactive and has no saved state" and SUSPENDED="The resource is inactive and has saved state"

2) I really think we need an entry state like "PENDING" or "DEFINED".
It will help in implementation relying on a best-effort scheduler to
match VMs and hosts, like EC2 does. This will be the state where
machines will wait for a host to be available to run on. Also, I don't
really think that a machine entering its life cycle in SUSPENDED state
is a good idea.

I tend to agree, but I'd like the terminology to be completely unambiguous... something like "NEW" [for this AS].

3) +1 to the "CRASHED", "ERROR" or "FAILED" state.

ABORT[ING|ED] = "The resource encountered an error and is aborting/has aborted".

What do you think?

Some of these transitions take a while so some way of indicating progress (especially interesting for long tasks like live migrations) would be useful. Would prefer a mechanism that worked universally for the API.

Sam

Extensions

State control

State	Transitions	Description
aborting	aborted	The resource encountered an error and is aborting
aborted	n/a	The resource encountered an error and has aborted
active	pause, restart, stop, suspend	The resource is active
resuming	aborting, active	The resource is becoming active and restoring state
pausing	aborting, paused	The resource is preparing to refuse new requests
paused	aborting, resume	The resource is refusing new requests
starting	aborting, active	The resource is becoming active
stopped	start	The resource is inactive and has no saved state
stopping	stopped, aborting	The resource is becoming inactive and destroying state
suspended	resume, stop	The resource is inactive and has saved state

Note: Stable states and user transitions in bold.