Samsung SM951 512GB M.2 PCIe SSDs in RAID 0 – Hitting 4.5GB/s

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ATTO & AS-SSD Benchmarks

ATTO v2.47

ATTO is one of the oldest drive benchmarks still being used today and is still very relevant in the SSD world. ATTO measures transfers across a specific volume length. It measures raw transfer rates for both reads and writes and places the data into graphs that can be very easily interpreted. The test was run with the default runs of 0.5KB through 8192KB transfer sizes with the total length being 256MB.

Single Drive:

ATTO SM951

Software RAID0:

ATTO SM951 RAID 0

Benchmark Results: ATTO showed the Samsung SM951 512GB M.2 PCIe SSD maxing out at 2259 MB/s read and 1583 MB/s in the standard overlapped I/O benchmark with one drive by itself. With the pair of drives setup as a striped dynamic volume in Windows 8.1 Pro we were able to get 4176 MB/s read and 3166 MB/s write! The read performance suddenly dropped off at the 1MB file size and never recovered.

ATTO SM951 at different queue depths

We changed the queue depth and found that once the drive went over ~4200 MB/s that the performance plummeted on the reads. We thought that the CPU frequency on our Intel Core i7-5960X could be an issues, but overclocking it up to 4GHz and enabling Turbo mode didn’t have any significant impact on performance. It might also be something with Windows 8.1, but we aren’t sure and haven’t tried this setup on other OS versions.

AS-SSD (1.7.4739.38088) Benchmark:

We have been running the AS-SSD Benchmark app for over some time now and found that it gives a broad result set. The programmer has worked very hard on this software and continues to make updates often so if you use it, show him some love and send him a donation. There are now three tests that are found within the tool and we’ll show the results from all three of them.

Single Drive:

asssd-sm951

Software RAID0:

asssd-raid0

Benchmark Results: AS SSD showed the single Samsung SM951 512GB M.2 PCIe SSD topping out at 1987 MB/s read and 1510 MB/s write in the sequential benchmark. With a dynamic striped volume we were getting 3515 MB/s read and 2989 MB/s write in the sequential benchmark. The 4K read and write speeds actually decreased with the RAID setup as did the drives access times. 

Single Drive:

asssd-sm951-copy

Software RAID0:

asssd-raid0-copy

Benchmark Results: The AS SSD copy benchmark showed the speed topping out at 1371 MB/s in the ISO test with one SM951 512GB M.2 PCIe SSD, but with two drives we were able to hit 1934 MB/s on the same workload! We noticed the AS SSD program test trace in the copy-benchmark actually slowed down in the RAID 0 setup, which is something we’ve never seen before with striped dynamic RAID.

Single Drive:

asssd-sm951-compression2

Software RAID0:

asssd-raid0-comp

Benchmark Results: Compression performance was similar between the single drive and dynamic volume other than their speeds.

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