MESOS-3421: Support sharing persistent volumes across task instances

[Anindya Sinha <an...@gmail.com>]

Now that mesos has introduced support for persistent volumes, the
persistent volumes that are created on a specific slave is offered to the
framework(s) as another resource. As a result, a task which needs RW access
to that persistent volume can use that resource.

Till this task is running, that persistent volume cannot be offered to the
framework(s) and hence would not be available for another task running on
the same agent.

Let us consider an use case wherein a service needs access to the same
persistent volume from multiple task instances running on the same agent
simultaneously, ie. when both (or multiple) of such task instances are
RUNNING. Since the persistent volume is not offered as a resource to the
framework(s) till a task that has grabbed it is still active, the
subsequent instances needed access to the same persistent volume is not
feasible.

To alleviate that scenario, we propose making persistent volumes "sharable"
(as optional). Default behavior can still be "non-sharable" but frameworks
may want to CREATE persistent volumes as "sharable" (which would need an
optional field in Resources.DiskInfo.Persistence). Hence, we would allow
"sharable" persistent volumes be offered as resources to the framework(s)
[matching role] even if it has been grabbed by a task already running on
the agent, so as that subsequent tasks can use that persistent volume.

Comments/concerns?

Thanks

Anindya

Re: MESOS-3421: Support sharing persistent volumes across task instances

[Anindya Sinha <an...@gmail.com>]

Sure. I will have something soon with an initial draft to be reviewed
within the community.

Thanks
Anindya

On Mon, Sep 21, 2015 at 11:14 AM, Vinod Kone <vi...@gmail.com> wrote:

> I think shared persistent volumes are a great feature addition!
>
> Couple things that need to be addressed
>
> --> Who gets charged for the shared disk quota if multiple tasks share
> them? I'm assuming the one who creates a RW copy?
>
> --> How does the resource handling logic work in Mesos if a resource is
> re-offered while still in use? I think this is the piece that needs some
> major thinking.
>
> It's worthwhile to start a design doc around this. Anindya, are you up for
> the task?
>
> Thanks,
>
> On Mon, Sep 21, 2015 at 11:00 AM, Anindya Sinha <an...@gmail.com>
> wrote:
>
> > Now that mesos has introduced support for persistent volumes, the
> > persistent volumes that are created on a specific slave is offered to the
> > framework(s) as another resource. As a result, a task which needs RW
> access
> > to that persistent volume can use that resource.
> >
> > Till this task is running, that persistent volume cannot be offered to
> the
> > framework(s) and hence would not be available for another task running on
> > the same agent.
> >
> > Let us consider an use case wherein a service needs access to the same
> > persistent volume from multiple task instances running on the same agent
> > simultaneously, ie. when both (or multiple) of such task instances are
> > RUNNING. Since the persistent volume is not offered as a resource to the
> > framework(s) till a task that has grabbed it is still active, the
> > subsequent instances needed access to the same persistent volume is not
> > feasible.
> >
> > To alleviate that scenario, we propose making persistent volumes
> "sharable"
> > (as optional). Default behavior can still be "non-sharable" but
> frameworks
> > may want to CREATE persistent volumes as "sharable" (which would need an
> > optional field in Resources.DiskInfo.Persistence). Hence, we would allow
> > "sharable" persistent volumes be offered as resources to the framework(s)
> > [matching role] even if it has been grabbed by a task already running on
> > the agent, so as that subsequent tasks can use that persistent volume.
> >
> > Comments/concerns?
> >
> > Thanks
> >
> > Anindya
> >
>

Re: MESOS-3421: Support sharing persistent volumes across task instances

[Vinod Kone <vi...@gmail.com>]

I think shared persistent volumes are a great feature addition!

Couple things that need to be addressed

--> Who gets charged for the shared disk quota if multiple tasks share
them? I'm assuming the one who creates a RW copy?

--> How does the resource handling logic work in Mesos if a resource is
re-offered while still in use? I think this is the piece that needs some
major thinking.

It's worthwhile to start a design doc around this. Anindya, are you up for
the task?

Thanks,

On Mon, Sep 21, 2015 at 11:00 AM, Anindya Sinha <an...@gmail.com>
wrote:

> Now that mesos has introduced support for persistent volumes, the
> persistent volumes that are created on a specific slave is offered to the
> framework(s) as another resource. As a result, a task which needs RW access
> to that persistent volume can use that resource.
>
> Till this task is running, that persistent volume cannot be offered to the
> framework(s) and hence would not be available for another task running on
> the same agent.
>
> Let us consider an use case wherein a service needs access to the same
> persistent volume from multiple task instances running on the same agent
> simultaneously, ie. when both (or multiple) of such task instances are
> RUNNING. Since the persistent volume is not offered as a resource to the
> framework(s) till a task that has grabbed it is still active, the
> subsequent instances needed access to the same persistent volume is not
> feasible.
>
> To alleviate that scenario, we propose making persistent volumes "sharable"
> (as optional). Default behavior can still be "non-sharable" but frameworks
> may want to CREATE persistent volumes as "sharable" (which would need an
> optional field in Resources.DiskInfo.Persistence). Hence, we would allow
> "sharable" persistent volumes be offered as resources to the framework(s)
> [matching role] even if it has been grabbed by a task already running on
> the agent, so as that subsequent tasks can use that persistent volume.
>
> Comments/concerns?
>
> Thanks
>
> Anindya
>