RN716X performance

My understanding is that 802.3ad improves throughput for multiple connections, but won't go over 10gb for a single connection (or over 1 gb if you were using bonding on gigabit). So it might not help in your test case anyway, unless you were running multiple tests in parallel. Other bonding modes might not have particular restriction - it is intended to make sure that bonding on a trunk doesn't create an out-of-order packet stream for the ultimate receiver, and also to make sure that a receiver on an unbonded connection doesn't see packet loss at the physical layer (because the trunk is carrying more data than the client's connection can handle).

I'd try a test with bonding off, since the performance is well below a single 10gb connection anyway. That will tell you if bonding itself is hurting performance. You might also try varying the MTU size.

But your hard drives won't go faster than about 165 MB/second per http://www.storagereview.com/seagate_nas_hdd_review - and you are not doing a large sequential file reads if you are moving a lot of documents around.

So my guess is you are limited by the drives or possibly by btrfs. You could use ssh on the NAS to do some internal tests to benchmark raw performance, taking the network out of the equation. Copying files to /dev/null is a good basic test.

Or (as a test) try removing the hard drives, and setting up the nas with a single SSD, and see how that performs. I'm not suggesting that you deploy with SSD, just that you should test with one to determine if the hard drives are the bottleneck.

Also, it might be useful to set up a multi-user test, and see how the aggregated throughput compares to your single-threaded test.