So then, let's factor in some aggregate controller efficiency e.g. 0.76
which is conservative because it was measured with SATA-III SSDs
and the extra overhead required by the SATA protocol:
x16 lanes @ 8 GHz / 8.125 bits per byte x 0.76 = 11.97 GB/second
Clock rate doubles at PCIe 4.0:
x16 lanes @ 16 GHz / 8.125 bits per byte x 0.76 = 23.95 GB/second
23,950 MB/second / 8 ~= DDR4-3000
Conclusion:
A PCIe 4.0 NVMe RAID controller with four U.2 ports in RAID-0 mode
should approximate the overall throughput of DDR4-3000 DRAM
particularly when advanced memory technologies like Intel's Optane
populate the storage devices. At PCIe 3.0, project DDR3-1500,
which is very close to DDR3-1600 performance.
Here's one source of data on raw SATA overhead:
http://www.thessdreview.com/our-rev...ing-3gbs-recorded-with-8-crucial-c400-ssds/3/
Using a cheap Highpoint 2720SGL and 8 x Crucial C400 SSDs,
best case READ was 3,041 MB/second.
That add-on card is PCIe 2.0 with an x8 edge connector,
and the 8b/10b legacy frame (10 bits per byte):
x8 @ 5 GHz / 10 = 4.0 GB/second raw bandwidth upstream
Measured 3.041 / 4.0 = 0.760
Hopefully, the higher protocol efficiency of NVMe
will improve on that raw overhead quite a lot.
MRFS
which is conservative because it was measured with SATA-III SSDs
and the extra overhead required by the SATA protocol:
x16 lanes @ 8 GHz / 8.125 bits per byte x 0.76 = 11.97 GB/second
Clock rate doubles at PCIe 4.0:
x16 lanes @ 16 GHz / 8.125 bits per byte x 0.76 = 23.95 GB/second
23,950 MB/second / 8 ~= DDR4-3000
Conclusion:
A PCIe 4.0 NVMe RAID controller with four U.2 ports in RAID-0 mode
should approximate the overall throughput of DDR4-3000 DRAM
particularly when advanced memory technologies like Intel's Optane
populate the storage devices. At PCIe 3.0, project DDR3-1500,
which is very close to DDR3-1600 performance.
Here's one source of data on raw SATA overhead:
http://www.thessdreview.com/our-rev...ing-3gbs-recorded-with-8-crucial-c400-ssds/3/
Using a cheap Highpoint 2720SGL and 8 x Crucial C400 SSDs,
best case READ was 3,041 MB/second.
That add-on card is PCIe 2.0 with an x8 edge connector,
and the 8b/10b legacy frame (10 bits per byte):
x8 @ 5 GHz / 10 = 4.0 GB/second raw bandwidth upstream
Measured 3.041 / 4.0 = 0.760
Hopefully, the higher protocol efficiency of NVMe
will improve on that raw overhead quite a lot.
MRFS
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