Im still having a hard time with SATA2 being saturated fully saturated by a HDD
Lets start with this. 1 GB/s = 8 Gbits/s
It has been shown by several reputable web sites that a modern day SSD will saturate out a SATA2 interface somewhere in the area of 275 GB/s (2200 Gbit/s) as you stated.
Using this site as reference:
https://hdd.userbenchmark.com/• A 2TB 5400 WD Red will read at 141 Mb/s (1128 Gbit/s)
• A 2 TB 7200 WD Gold will read at 159 Mb/s (1272 Gbit/s)
• The saturation point of SATA2 is roughly 275 GB/s (2200 Gbit/s)
• Ergo, the commonly used HDD in a MSS feeds data into the MSS server's SATA2 interface at roughly half of it's capacity
So the MSS SATA driver efficiency would have to be less than 60% efficient for the interface to be saturated. That's highly unlikely but would be easy enough to confirm by benchmarking the drives in a single and multi drive MSS.
Leaving the theoretical, HD 1080p BluRay was introduced in 2006, If SATA2 couldn't handle HD playback, how was it being done before late 2009 when SATA3 was introduced?
So what is the data transfer rate when playing a video?
•
4K BluRay has a maximum supported bitrate of 128 Mbits/s for the largest triple layer discs.
• So the slowest portion of the platter in a 5400RPM disk is still at least 8 times higher bandwidth than the peak bandwidth of a 4K BluRay
• 1080p needs far less bandwidth than 4k
• Surprisingly even today, the current 1080p blue ray drives are equipped with... wait for it, SATA1.1
So I don't see how SATA2 could be an issue when playing back recorded BluRay. That leaves us with the other two variables, CPU and NIC.
The 2.5Ghz e6XXX series Core2 Duo, the 3.0+ e6XXX series Pentium, the 2.5 Ghz e8XXX series Core2 Duo, and the QXXXs series quad cores all have a sufficient FSB to run 1080p. In fact, even the mid range & higher Ghz Conroes (Core2 Duo) did it just fine.
What's the CPU that's in the NAS you got?
My intent in posting all this is not to negate your experience of swapping in your Reds to a NAS with the result of having good video playback. It only leads one to think the issue of stutter on the MSS may not have been caused by the SATA2. Did you happen to benchmark the data transfer rates of each device before and after?
Is it possible the issue may have been how the NIC was setup?
Anyone else with video playback experience on the MSS care to jump in?