mesos git commit: Added discussion of multiple frameworks sharing the same role.

[ji...@apache.org]

Repository: mesos
Updated Branches:
  refs/heads/master 294460739 -> 6d0619e2e


Added discussion of multiple frameworks sharing the same role.

Review: https://reviews.apache.org/r/41905/


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/6d0619e2
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/6d0619e2
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/6d0619e2

Branch: refs/heads/master
Commit: 6d0619e2e1fbf78411f881f431269539c7d24565
Parents: 2944607
Author: Neil Conway <ne...@gmail.com>
Authored: Mon Jan 4 17:29:03 2016 -0800
Committer: Jie Yu <yu...@gmail.com>
Committed: Mon Jan 4 17:29:03 2016 -0800

----------------------------------------------------------------------
 docs/roles.md | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/6d0619e2/docs/roles.md
----------------------------------------------------------------------
diff --git a/docs/roles.md b/docs/roles.md
index bbc52ac..af1adad 100644
--- a/docs/roles.md
+++ b/docs/roles.md
@@ -55,6 +55,25 @@ start the framework. How to do this depends on the user interface of the
 framework you're using; for example, Marathon takes a `--mesos_role`
 command-line flag.
 
+### Multiple frameworks in the same role
+
+Multiple frameworks can use the same role. This can be useful: for example, one
+framework can create a persistent volume and write data to it. Once the task
+that writes data to the persistent volume has finished, the volume will be
+offered to other frameworks in the same role; this might give a second
+("consumer") framework the opportunity to launch a task that reads the data
+produced by the first ("producer") framework.
+
+However, configuring multiple frameworks to use the same role should be done
+with caution, because all the frameworks will have access to any resources that
+have been reserved for that role. For example, if a framework stores sensitive
+information on a persistent volume, that volume might be offered to a different
+framework in the same role. Similarly, if one framework creates a persistent
+volume, another framework in the same role might "steal" the volume and use it
+to launch a task of its own. In general, multiple frameworks sharing the same
+role should be prepared to collaborate with one another to ensure that
+role-specific resources are used appropriately.
+
 ## Associating resources with roles
 
 A resource is assigned to a role using a _reservation_. Resources can either be