RAID's write speed on large files suddenly tanking randomly

[DrSNAFU]

tl;dr: When recording with fraps, dxtory or just generating a large file, my write speed fluctuates wildly, ranging from 140-70, but also dropping to as low as 2mbps, causing lag and maxing out disk activity %.


I've been recording gaming sessions off and on for a couple months now, but a few weeks ago, I started getting a problem with fraps. While recording, the frame rate will suddenly go into the toilet and my hard drive will start thrashing continuously, interfering with my game. Stopping the recording instantly fixes the issue. Nothing in the game seems to be causing it, it happens with recording plain desktop even. I tried using dxtory, another recording program, and it too seems to have this issue. It even has a disk write speed tester and it registered inconsistent write speeds, wildly swinging between 140mbps and dropping to single digits at times, sometimes nosediving down to 2mbps and staying there until I end the test.

I went back to fraps and watched the Resource Monitor when the issue kicked in. The recording speed went from 54mbps (give or take) down to 3-5 during those incidents while the highest active time pegged up to 100% and stayed there. 100% access time to get 2mbps write speed? Not good. No other programs appear to be interfering from what I can tell. I'm worried there's something bad wrong with my RAID 1 or the drives themselves.


On a possibly related issue, a few weeks ago (can't remember if it happened before or after this started) I had a power loss while gaming. I recovered and restored the RAID but later that night the computer locked up hard, completely. I had to manually shut the computer off. I thought it was just a bit of fizz in the ram after the power loss but it happened again last week during a periodic MBAM scan. It's got me worried.

Any help or insight would be appreciated.

 

[DrSNAFU]

I can get the issue to happen pretty reliably. Just create a large file. dxtory's speed tests creates a dummy file and fraps creates large movie files. Both causes the issue to happen.

As I watch in Resource monitor with fraps recording, the disk activity goes at 31-36 MBps and 12-16% highest active time for a while, before instantly changing to 6-9 MPps and 100% highest active time, slowing everything down.


Included a screenshot of the occurrence. You can see from the graph the very clear marker between normal recording and when my HDD array wigs out.

I've tried disabling my antivirus entirely, no change. Ran CrystalDiskInfo, came up clean. I'm not sure what's going wrong.

 

[DrSNAFU]

For the record, I've found what the problem was. After defragging (it went 10 passes) the recording is now smooth and doesn't drop to nothing anymore. Apparently writing and deleting large files over and over again is murder on the fragmentation.

[ISSUE RESOLVED]