if you “burst” into another datacenter because of unavailable “local” resources
do you contract when resources are free? If your purpose of bursting is the
use case of an on-prem site bursting into a public provider it would seem
logical the contraction would be desired to free that public (and presumably
more costly) resources are released. This is amplified perhaps if you end up
in multiple DC’s if on each local resource contention a different “foreign”
cluster is chosen to burst into — unless you further plan to bias towards
keeping your “burst tasks” in a same DC if possible (e.g. given DC-{A,B,C} once
you burst from DC-A to DC-B you’d prefer B over C for future task launches) or
maybe you don’t care (or maybe this is a policy?)
> On Jul 15, 2016, at 6:46 PM, DhilipKumar Sankaranarayanan
> <[email protected] <mailto:[email protected]>> wrote:
>
> Hi All,
>
> I got a chance to bring this up during yesterdays Community Sync. It was
> great discussing with you all.
>
> As a general feedback the role of policy engine in the design needs to be
> clearer, i will update the Document with more information on PE very soon.
>
> We are yet to get more insight on the License issues like bringing in a
> Mozzilla 2.0 library into an Apache 2.0 project.
>
> It will be fantastic to get more thoughts on this from the community so
> please share if you or your organisation had thought about it.
>
> HI Alex,
>
> Thanks again.
>
> a) Yes you are correct, thats exactly what we thought, a Framework could
> simply query and learn about its next step (bursting or load balancing).
> b) We are currently thinking that the Framework will run in only one place
> and should be able to connect to other datacenters. Each data centres could
> have some Frameworks running the local and some part of a federation.
>
> Regards,
> Dhilip
>
>
> On Thu, Jul 14, 2016 at 9:17 AM, Alexander Gallego <[email protected]
> <mailto:[email protected]>> wrote:
>
>
> On Thu, Jul 14, 2016 at 2:40 AM, DhilipKumar Sankaranarayanan
> <[email protected] <mailto:[email protected]>> wrote:
> HI Alex,
>
> Thanks for taking a look. We have simplified the design since the
> conference. The Allocation and Anonymous modules where only helping us to
> control the offers sent to the frameworks. Now we think that Roles and Quota
> in Moses elegantly solve this problem and we could take advantage of it.
>
> Sounds good, given that the design is entirely different now, can you share
> some of these thoughts.
>
>
> The current design does not propose Mesos Modules, the POC we demonstrated @
> the mesoscon is slightly out of date in that respect.
>
> The current design only enforces that any Policy Engine implementation should
> honour certain REST apis. This also removes Consul out of the picture, but
> at Huawei our implementation would pretty much consider Consul or something
> similar.
>
> 1) Failure semantics
> I do agree it is not straight forward to declare that a DC is lost just
> because framework lost the connection intermittently. Probing the 'Gossiper'
> we would know that the DC is still active but not just reachable to us, In
> that case its worth the wait. If the DC in question is not reachable from
> everyother DC, only then we could come to such conclusion.
>
>
>
> how do you envision frameworks integrating w/ this. Are you saying that
> frameworks should poll the HTTP endpoint of the Gossiper?
>
>
> 2) Can you share more details about the allocator modules.
> As mentioned earlier these modules are no longer relevant we have much
> simpler way to achieve this.
>
> 3) High Availability
> I think you are talking about the below section?
> "Sequence Diagram for High Availability
> (Incase of local datacenter failure)
> Very Similar to cloud bursting use-case scenario. "
> The sequence diagram only represents flow of events in case if the current
> datacenter fails and the framework needs to connect to a new one. It is not
> talking about the approach you mentioned. I will update doc couple more
> diagrams soon to make it more understandable. We would certainly like to
> have a federated K/V storage layer across the DCs which is why Consul was
> considered in the first place.
>
>
> Does this mean that you have to run the actual framework code in all of the
> DC's ? or you have yet to iron this out?
>
>
>
> 4) Metrics / Monitoring - probably down the line
> The experimental version of gossiper already queries the maser at a frequent
> interval and exchange it amongst them.
>
> Ultimately DC federation is a hard problem to solve. We have plenty of use
> cases which is why we wanted to reach out to the community, share our
> experience and build something that is useful for all of us.
>
>
> Thanks !! excited about this work.
>
> Regards,
> Dhilip
>
>
> On Wed, Jul 13, 2016 at 7:58 PM, Alexander Gallego <[email protected]
> <mailto:[email protected]>> wrote:
> This is very cool work, i had a chat w/ another company thinking about doing
> the exact same thing.
>
> I think the proposal is missing several details that make it hard to evaluate
> on paper (also saw your presentation).
>
>
> 1) Failure semantics, seem to be the same from the proposed design.
>
>
> As a framework author, how do you suggest you deal w/ tasks on multiple
> clusters, i.e.: i feel like there have to be richer semantics about the task
> at least on the mesos.proto level where the state is STATUS_FAILED_DC_OUTAGE
> or smth along those lines.
>
> We respawn operators and having this information may allow me as a framework
> author to wait a little longer before trying to declare that task as dead
> (KILLED/FAILED/LOST) if I spawn it on a different data center.
>
> Would love to get details on how you were thinking of extending the failure
> semantics for multi datacenters.
>
>
> 2) Can you share more details about the allocator modules.
>
>
> After reading the proposal, I anderstand it as follows.
>
>
> [ gossiper ] -> [ allocator module ] -> [mesos master]
>
>
> Is this correct ? if so, you are saying that you can tell the mesos master to
> run a task that was fulfilled by a framework on a different data center?
>
> Is the constraint that you are forced to run a scheduler per framework on
> each data center?
>
>
>
> 3) High availability
>
>
> High availability on a multi dc layout means something entirely different. So
> are all frameworks now on standby on every other cluster? the problem i see
> with this is that the metadata stored by each framework to support HA now has
> to spans multiple DC's. It would be nice to perhaps at the mesos level
> extend/expose an API for setting state.
>
> a) On the normal mesos layout, this key=value data store would be zookeeper.
>
> b) On the multi dc layout it could be zookeeper per data center but then one
> can piggy back on the gossiper to replicate that state in the other data
> centers.
>
>
> 4) Metrics / Monitoring - probably down the line, but would be good to also
> piggy back some of the mesos master endpoints
> through the gossip architecture.
>
>
>
> Again very cool work, would love to get some more details on the actual
> implementation that you built plus some of the points above.
>
> - Alex
>
>
>
>
>
>
>
> On Wed, Jul 13, 2016 at 6:11 PM, DhilipKumar Sankaranarayanan
> <[email protected] <mailto:[email protected]>> wrote:
> Hi All,
>
> Please find the initial version of the Design Document
> <https://docs.google.com/document/d/1U4IY_ObAXUPhtTa-0Rw_5zQxHDRnJFe5uFNOQ0VUcLg/edit?usp=sharing>
> for Federating Mesos Clusters.
>
> https://docs.google.com/document/d/1U4IY_ObAXUPhtTa-0Rw_5zQxHDRnJFe5uFNOQ0VUcLg/edit?usp=sharing
>
> <https://docs.google.com/document/d/1U4IY_ObAXUPhtTa-0Rw_5zQxHDRnJFe5uFNOQ0VUcLg/edit?usp=sharing>
>
> We at Huawei had been working on this federation project for the past few
> months. We also got an opportunity to present this in recent MesosCon 2016.
> From further discussions and feedback we have received so far, we have
> greatly simplified the design.
>
> Also I see that no one assigned to this JIRA now could i get that assigned to
> myself ? It would be great to know if there is anyone willing to shepherd
> this too.
>
> I would also like to bring this up in the community Sync that happens
> tomorrow.
>
> We would love to hear your thoughts. We will be glad to see collaborate with
> you in the implementation.
>
> Regards,
> Dhilip
>
>
> Reference:
> JIRA: https://issues.apache.org/jira/browse/MESOS-3548
> <https://issues.apache.org/jira/browse/MESOS-3548>
> Slides:
> http://www.slideshare.net/mKrishnaKumar1/federated-mesos-clusters-for-global-data-center-designs
>
> <http://www.slideshare.net/mKrishnaKumar1/federated-mesos-clusters-for-global-data-center-designs>
> Video :
> https://www.youtube.com/watch?v=kqyVQzwwD5E&index=17&list=PLGeM09tlguZQVL7ZsfNMffX9h1rGNVqnC
>
> <https://www.youtube.com/watch?v=kqyVQzwwD5E&index=17&list=PLGeM09tlguZQVL7ZsfNMffX9h1rGNVqnC>
>
>
>
>
> --
>
>
>
>
>
> Alexander Gallego
> Co-Founder & CTO
>
>
>
>
> --
>
>
>
>
>
> Alexander Gallego
> Co-Founder & CTO
>
