In the past with NW 7.6 and DD integration, I saw a lot of implementation with 1 max session / device.  The admin told me they saw huge difference in dedupe ratio.  So, for my DD 7.6.x, 8.1.1 and DD boost integration in the last few yrs, I use 1 target session and 4 max sessions / device in 7.6.x and 1 target session and 6 max sessions / nsrmmd (excluding the nsrmmd for read).  The NW 8 integration doc suggests a max of 60 session.  I only use 30 sessions / device and keep the session / nsrmmd at 6. 

Recently, I did review the NMDA 1.6 doc and found the following (I config 1 max session to 1 nsrmmd anyway for database pool). 

Parallel backups to AFTD or Data Domain devices are not multiplexed. However, the use of multiple concurrent streams to the same device can impact the overall throughput and deduplication ratio. Minimize the number of sessions to any device that includes deduplication by setting the target session attribute value of the device to 1.

The document has not mentioned max session.  Should we keep the device for database backup at 1 max session / nsrmmd?  For normal file dedup, will it make affect the dedupe ratio a lot if I set it from 6 max sessions / nsrmmd to 10 max sessions / nsrmmd?