What is the best way to go from a closed JIRA to a community-driven JIRA?

[Richard Saffell]

We have about 10 years of ideas, comments, and proprietary information in our JIRA.  We want to start to allow our community to create JIRAs with their ideas, add comments to existing JIRAs, and vote/watch issues.

How can we open up our JIRA installation without giving any access to our existing information?

For example, should we create a new group (jira-community) and just grant permissions to specific issues to that group?  Along with the permission to create, vote, and watch issues?

[mlassau_atlassian]

One way to achieve this is by having two separate and distinct JIRA servers - one internal and one external.

This is indeed what we do at Atlassian.
On jira.atlassian.com we report bugs and customers can report bugs, and raise improvement requests.

However we also have an internal server where we do all our feature work.
All bug fix work on the bug fix branch is tracked on the public server. 
Details of work happening on master (trunk) is tracked on the internal server, but if there is a linked public issue (eg a feature request from customers), then we add info there to inform the customers and resolve it with an appropriate version number etc. 

You can keep links on issues between the two instances - this just works out of the box once you configure them with "Application Links".
Sometimes we want to copy an issue from one instance to the other, so we use the Remote Issue Copy plugin (available on Marketplace for free).