Application:

• A ton of continuous writing.  We will do DVR like recording on multiple channels.
• A lot of reading for media streaming
• We would like some data protection in case of disk failures

We would like to do do a tiered storage with multiple SSDs and traditional HDDs.  Here are the questions:

• What is the best tiered storage set up?  Mirrored?  Parity?  Double Parity?
• Number of SSDs vs. number of HDDs?  We are thinking 16 bay head unit with 2 JBOD attachments with each up to 90 drives for total of 180 JBOD drives.
• Ideal mixture of SSDs vs. HDDs for best performance.

Thank you for any suggestion in advance!

"What is the best tiered storage set up?  Mirrored?  Parity?  Double Parity?"

Mirrored has less write overhead.  Parity can cause up to four disk accesses per write, double five.  Mirrored is two.

"Ideal mixture of SSDs vs. HDDs for best performance."

To find the ideal, you are really going to need to get your application up and running with your workload.  Maybe the JBOD vendor has done some testing to give you an idea of where to get started with their particular configuration.