OT: Read Write Disk Speeds

[Bert 49]

I have been having issues with transcoding not starting and some general performance issues with my computer.  I have a 8 Bay Sans Digital RAID tower hooked up to my computer setup in what I believe is called unraid (it's just a bunch of drives).  The issues I see involve typically high bit-rate MKV and MPV files not streaming and inconsistent live tv.  Both problems actually seem to be inconsistent.  Every couple of months it seems that the tower goes into it's boot sequence where it checks each drive twice and then all the lights start up.  Sometimes it seems to get stuck in this boot sequence.  More consistently, if I am using MakeMKV, recording tv, and transcoding the computer is very slow to respond and herky jerky (to use a technical term).  So my suspicion is maybe a cheap raid controller (RocketRAID 642L SATA) or cheap cables (although I am on the second set) or something else.  So I went to test my drive speed using CrystalDiskMark  and am getting 145 MB/s sequential read and 146 sequential write on a 7200 RPM Deskstar.  103.9 and 98 on a WD Red.  This is a modern computer with the newest SATA protocol (6.0 GBPs which I know is just for pretend).  

 

My question is really, what kind of real world read and write times should I see?  

 

In your vast experience do you think my slowness would be caused most likely by the cheap/maybe defective card?  Cables?  A setting I am missing?

 

Thanks in advance for pointing me in the right direction.

Edited October 28, 2015 by Bert