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Inconsistent benches from my 2x Performance Pro 256 in RAID 0

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I'm setting up a new computer with 2 Performance Pro 256 GB SSDs in a RAID 0 configuration and ran into some weird numbers when I was doing some benchmarks.


My first question is: is it normal for random 4k read/write performance to drop when using RAID 0 vs individual drives? (My guess would be that it's because I was using msahci drivers before I set up the RAID, then went to the IRST drivers after...)


Individual Drives:



RAID 0 (before/after enabling write caching):



More importantly, I'm wondering if the anomalies I'm seeing in ATTO are anything to be concerned about. Sometimes 16K, 32K reads and 2048K writes seem to be a LOT slower than they should be. If I limit my test range to between 16K and 2048K the numbers seem fine though, so I don't know if it's a 'real' problem or just something having to do with ATTO.





I used both drives individually (one Windows 7, one Windows 8 beta) in my older system for about a month before putting together my new system, and they seem to be working fine. And yes, I did a secure erase on both before RAIDing and formatting in the new system.

Any thoughts? (Thanks in advance...)

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So are you saying the dips in 16K/32K reads and 2048K writes are normal? Personally I don't remember seeing an ATTO screenshot with dips that large. 16K reads are nearly 1/3 the speed of the 8K reads in one of those pictures...


I'm running a clean Windows 7 install with only the motherboard chipset drivers and the IRST software installed. I don't have an antivirus or anthing else installed. I know that what you have installed and what services/etc are running can make a difference, but I didn't see it have as much an effect as people usually suggest. In my first picture I showed AS-SSD results for both drives individually -- The one labeled as "F:" is faster than the other, even when it's the OS drive and the other was just secure erased. (Here's a picture of that drive as the OS drive, write cache disabled obviously.)



Unfortunately I wasn't testing the individual drives with ATTO so I don't know if the 16K/32K read speed is lower on one, both, only when used as a system drive, or only in RAID 0.

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I appreciate the advice, but the ATTO screenshot that I wrote "another full test, much later" on was done after at least 20 hours idle on-time. In fact, the only times I've gotten 'normal' results (no dips in transfer rate on ATTO) were when I retested immediately after getting the lower scores -- twice on just the 16K-2048K range, once over the entire range.


Honestly, if I can get 'only' 370 MB/s for 16K chunks and 500 MB/s for 32K reads, and writes of 725 MB/s for 2M that's still really fast and I'll probably never notice it in real world usage. I just want to make sure it's not an early warning sign that something is wrong with one of the drives.

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