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Strip performance issue while creating RAID across PCIE slots

(@tksonix-uk)
Active Member

I bought two Accelssior 4m2 pcie raid card for my mac pro 2019, and put them in the two 8-lane slots.

I filled both card with Samsung 970 evo plus 500GB SSD, which has R/W speed of over 3000MB/s.

When I create RAID 0 volume by choosing 4 of the 8 drives, with 2 SSDs from one Accelssior card and 2 from the other.

In theory, each nvme SSD takes 4 lanes, then 2 of them on each card should max out the 8 lanes of the Accelssior card, so two Accelssior cards results in speed of 16 lanes.

If the above is correct, when I create RAID 0, in theory I should have over 10GB/s speed with PCIE 3.0 x16.

However, I only have maximum of 7000MB/s speed, which is only about PCIE 3.0 x8.

And by the way, with Apple raid in macos’s disk utility, if I create RAID using card from both Accelssior cards, it only gives me around 300MB/s speed, very strange.

Could someone explain this?

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Topic starter Posted : 21/09/2020 3:04 pm
(@softraid-support)
Member Admin

The max throughput on the Mac Pro is about 7000 MB/s. Nothing we know you can do to get better.

 

I have not tested Apple RAID 0, 300 is goofy slow, unless you made it encrypted APFS, which is very slow.

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Posted : 21/09/2020 9:13 pm
(@tksonix-uk)
Active Member
Posted by: @softraid-support

The max throughput on the Mac Pro is about 7000 MB/s

Well I have seen the sonnet x16 raid card performing over 10GB/s in their website benchmark sheet. And I’ve seen benchmark results over 8000MB/s for many times.

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Topic starter Posted : 22/09/2020 12:52 am
(@softraid-support)
Member Admin

I never got that in AJA with the Sonnet card. If I remember, 7300 was the max I saw.

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Posted : 22/09/2020 3:20 am
(@tksonix-uk)
Active Member

@softraid-support Here is some benchmark results sourced from YouTube. The Blackmagic disk mark is going to be slower, which I only got around 5500MB/s speed; while the atto bench mark gives me 7000MB/s speed.

 

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Topic starter Posted : 22/09/2020 4:15 am
(@softraid-support)
Member Admin

I can try the Sonnet again, I have Samsung blades to put into it. I just never say 10GB/s, but that is impressive!

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Posted : 22/09/2020 12:44 pm
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