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DVDI Isolator Overview and Roadmap.md

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DVDI Isolator Overview and Roadmap

Persistent Storage for Mesos

Certain classes of applications, such as databases, require long term access to persistent storage.

Issue and Workarounds

Techniques are available to run these types of workloads on Mesos, but sometimes the methods involved are essentially work-arounds that amount to using storage not managed by Mesos

Workaround: Use direct attached storage

  • Locks your workload to a single cluster node after first run, defeating an essential benefit of a cluster scheduler - the dynamic assignment of workloads to any, or the most appropriate, cluster node

Workaround: Use external storage such as NFS from within the application

  • Mesos is oblivious to this use of storage and cannot deliver in its role as a data center OS, offering centralized management and audit
    • This violates a key best practice premise of 12 factor apps by requiring maintenance of run time platform configuration inside the app itself

Better solution

  • Use the new DVDI Isolator

What is the DVDI Isolator Module

Mesos has a rich facility to support plugins that add features.

The DVDI Isolator is a module, which is a binary plugin for Mesos.

In particular, it is an isolator module, which is a module that runs on agent cluster nodes and can interact with resource usage

Features of the Mesos DVDI Isolator

  • Manages external storage - storage that is network attachable to multiple cluster nodes,
  • Allows an application workload to be configured with a declarative statement describing its storage needs
    • This declaration is managed by Mesos. For example it can be done using the Marathon API.

Manages full volume mount lifecycle

  • Allows a volume to be composed or allocated and formatted from a pool upon first task run.
  • Allows subsequent task runs to re-attach to the volume, even if the task runs on a different cluster node each time

Supports Many storage types

  • AWS EC2 EBS
  • EMC ScaleIO
  • EMC XtremIO
  • many others too including NFS

Some of these storage types allow declarative specification of a rich set of storage attributes such as IOPs

The DVDI Storage Interface

DVDI stand for Docker Volume Driver Interface.

It leverages the internal storage volume interface of Docker.

  • The rapid investment growth in Docker related infrastructure is resulting in widespread implementation of the Docker interface by all popular forms of storage

Why wasn't Docker sufficient by itself

  • The DVDI Isolator allow a Mesos workload to take advantage of any storage with a Docker interface but does not require that application to run in a Docker container
  • Many Mesos workloads do not run in Docker containers

DVDI Isolator Architecture

DVDI Futures

Short term roadmap: Improvements to integration

  • use "first class" workload attributes to specify storage characteristics, instead of environment variables
  • Allow concurrent use with Mesos containerizer isolator

Longer term roadmap

  • Enable Mesos management of tiered pools of storage
  • Enable implementation of storage providers as a Mesos Framework, reporting storage as a global or cluster wide resource, with advertised attributes to guide workload placement