Question M.2 SSD RAID0 "Upgrade FAIL" - help?

xXPat

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Dell Precision 7760 super high-end laptop. Accommodates up to 4 M.2-2280 SSDs. The first one is the system boot drive; the other 3 are available for creating a RAID0 array.

Original configuration: (2) Sabrent Rocket 4tb m.2 SSD's RAID0'd together to create a 2-SSD 8tb volume that consistently performed 6200-6400MB/s seq read (Crystal Diskmark8).

Obviously that's already pretty darned good performance, but the drive in question hosts several VMs that are very I/O intensive, so I wanted faster.

I was only using about half of the resulting 8TB volume so decided to "Upgrade" by replacing (2) Sabrent Rocket 4tb SSD with (3) 2tb Samsung 980 Pro SSDs, creating a 6tb volume. I figured the 980 pro is consistently rated the top performing SSD on the market, and 3 drives RAID0'd together should be close to 50% faster than just two.

Did the "Upgrade". Performance literally cut in half on Crystal Diskmark - 3249 Seq Read vs. 6500 before the "upgrade". And the new configuration has 3 M.2s vs. just two! More importantly, the performance of my VMs has degraded markedly.

Something doesn't add up here... Yeah sure, maybe the Rocket is faster than the 980 Pro. But it would have to be many TIMES faster for a 3-drive RAID0 volume to so badly underperform a 2-drive volume. Feels to me like something unobvious went wrong and I feel like I'm not seeing it clearly yet.

Specific questions:

1. Am I correct to assume the best way to get max performance from RAID0 is to use all 3 available M.2 slots, not just two? Is there any scenario where 2 makes more sense than 3?

2. If the objective is max performance for hosting VMs and I need at least 5tb total capacity, what is the best model/brand of SSD instead of the 3 new 980 Pro's I just installed??

I'm assuming 3x2tb should perform better than 2x4tb--is that right? If so, the 980 Pros most be horribly slower than the Sabrent Rockets I was using. But I should also mention that I've noticed that the performance of the Sabrent RAID0 array degrades dramatically when the SSDs get too hot on very large file transfers. One of the motivations for the "upgrade" was I figured the 980 Pro's would be less likely to degrade under high use/heat situations.

I'm tempted to try 3x2tb Sabrent Rockets since the 4TB version performed well in a 2-drive array. But something about this whole thing just doesn't add up. The 980 Pros are very well rated. 3 of them should have performed better than 2 Rockets. But they perform less than HALF as well. Feels to me like adding a 3rd SSD somehow complicated the situation or introduced a new problem, but I can't figure out what.

Thanks in advance for any advice!!!
 

xXPat

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Thanks for the reply but I don't understand your logic. Writing the same amount of data to two (or three) drives in parallel has to be faster than writing that same data to just one drive. The performance of my Sabrent Rocket RAID array at 6500 MB/s seq read exceeds the rated performance of any single SSD, seemingly disproving your statement . What am I missing?
 

xXPat

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Thanks for the link. I read the article, but it seems pretty clear it's not relevant to this situation. The article is about all the good reasons it makes much more sense to just get a single 1TB SSD instead of (2) 500GB SSD's RAIDed together.

Please enlighten me, @Darkbreeze. What's an example model or part number for the 8TB M.2 SSD you seem to think I should favor? Oh, you say nobody makes 8TB M.2's yet? Doesn't that lead one to the conclusion that the only way to get >4GB capacity is RAID or Windows spanned volumes?
 

USAFRet

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Original configuration: (2) Sabrent Rocket 4tb m.2 SSD's RAID0'd together to create a 2-SSD 8tb volume that consistently performed 6200-6400MB/s seq read (Crystal Diskmark8).

Obviously that's already pretty darned good performance, but the drive in question hosts several VMs that are very I/O intensive, so I wanted faster.
Are those Sabrents PCIe 3.0 or 4.0?

Sequential numbers are NOT the same as I/O performance.

A RAID 0 with NVMe drives can show big sequential numbers, and be actually slower in user facing operation.
https://www.tomshardware.com/reviews/samsung-950-pro-256gb-raid-report,4449.html

Is there a specific reason these VMs need to be in a single volume?
 

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