To start, here's my build: https://pcpartpicker.com/list/GLshPs -- NOTE it has parts in it for the NAS I put together as well.
The basic setup is a 500GB SSD for OS, and a 6TB (3x3TB 7200 Seagate Constellation drives w/128MB cache) RAID5 array.
The long and the short of it is that I noticed my whole computer locking up when steam tried to update some of my games. I thought it was steam, but I've now seen it on other platforms that try to update large quantities of data at a time. I'm not sure what's kicking it off, but basically, when the issue happens, disk usage goes to 100% (though very little disk *activity* takes place), and I look at my resource monitor, I notice HUGE (25,000 ms+) response times for various disk activity.
I've done many things to try to diagnose and fix this, including a full surface test, and installing the latest drivers from Intel, but that actually made RST go kaput. It will not run, and when I try to bring up the application, it says, "An unknown error occurred while running this application. If the problem persists, please restart your computer or try reinstalling the application." Of course, I've tried both options multiple times.
I meant to get a thread up much sooner, but ran into some issues recovering my account/pw here, and forgot about it for awhile, but it's starting to become quite a nuisance.
I had a thread going on steam for quite a while (because I thought that's what the issue was), which you can see here: HDD usage at 100% after adding new location [raid5] :: Hardware and Operating Systems
Now, since then, I still haven't been able to fix the problem, but I the more I think about it, the more I think it has to do w/the cache on the hard disks. It seems that when it switches data out of the cache is when it's triggering this issue (this is a COMPLETE guess, btw). For instance, starting up a game that has to load a lot of files will take FOREVER, but once I do that, I'm good to go, until I load a different game, which will take forever if it loads a lot of files.
If you want links to the pictures i posted w/out having to deal w/those silly warnings, I'll compile them below.
Surface test: http://phroztnet.org/screen/ts/20170124_surfacetest.png
Updating via steam showing nothing going on, but disk at 100%: http://phroztnet.org/screen/ts/20170203_steam.png
2 GB update on battlefield 1 that did not show this issue: http://phroztnet.org/screen/ts/20170207_origin.png
60 GB dl on Uplay that started smooth... : http://phroztnet.org/screen/ts/20170207_uplay.png
Then got ugly: http://phroztnet.org/screen/ts/20170207_uplay-01.png
Got better after the "stuck" files got cleared out: http://phroztnet.org/screen/ts/20170207_uplay-02.png
Screenshots of bad response times
Looking back at these response times, these are nothing compared to what I see now... I can hit 14k response times with ease, and I've even seen 25k response times.
I would be more than happy to run more tests/diagnostics/whatever. I got burned out for a while trying to fight this, but I'm willing to try again.