SATA to PCIE adapter(s): How many hard drives does it take to saturate a PCIE 16x interface?

[Joshua5684]

Obviously you can do a calculation based on the specs of the drives, but that's not interesting. I'd like to see it tested and I want to see all the drives plugged in to the same PCIE 16x slot. Do adapters required to do this exist?

[FloRolf]

i know you don't want to calculate but ... Pcie 4.0 x16 does 32gbyte/s and a standard harddrive maaaaybe 200mbyte/s. Which means you need roughly 160 Harddrives to reach that. Sooooooo good luck testing that out. 

[jaslion]

Why test it? The calculations will give you a theoretical max and in practice things will simply usually be slower as there is always an overhead.  If you want to see this done just look up some server video's or articles it's plenty common there.

[TorC]

@Joshua5684 -- do you mean like this?

Try it!

[Joshua5684]

6 minutes ago, jaslion said:

Why test it?

This is Linus Tech Tips

[Joshua5684]

4 minutes ago, TorC said:

do you mean like this?

That might be one piece of the puzzle. I want it to be able to plug into a single 16x slot. With this, you'd need 20 1x slots... or more adapters! Are there 1x to 4x, 4x to 8x, and 8x to 16x adapters? Maybe it can be built up to a single 16x slot.

[mariushm]

pcie 2.0 is 500 MB/s per lane so x16 is 8 GB/s.

pcie 3.0 is 970 MB/s per lane so x16 is 15.5 GB/s

pcie 4.0 is 2 x 970 MB/s per lane so x16 is ~ 31 G B/s

 

due to overhead, substract around 5% of that ... overhead means basically ... data going on pci-e is arranged in data packets and each packet has a few bytes of information that's not actually data, so not 100% of the transfer is your actual data transfer from a sata device to your processor or whatever.

 

You usually don't have sata controllers or sas controllers that use 16 pci-e lanes, at most you'll see 8 pci-e lanes.

You could use a pci-e switch IC to split the x16 into 16 pci-e x1 slots, and then plug into each slot a 2 port sata controller ... with two SSDs you could get close to around 540-560 MB/s per SSD so when both SSDs are used at same time, the sata controller will probably reach around 920-950 MB/s ...

There's 4 port sata controllers that use 2 pci-e lanes, same story ... just multiply 560 MB/s a single sata port can do by 4 and you get 2.4 GB/s ... which is more than what 2 pci-e 3.0 lanes can do, but less than 4 lanes.

 

[Blue4130]

10 hours ago, Joshua5684 said:

That might be one piece of the puzzle. I want it to be able to plug into a single 16x slot. With this, you'd need 20 1x slots... or more adapters! Are there 1x to 4x, 4x to 8x, and 8x to 16x adapters? Maybe it can be built up to a single 16x slot.

https://www.broadcom.com/products/storage/raid-controllers/megaraid-sas-9365-28i

This one has 28 ports on one slot.

 

https://www.broadcom.com/products/storage/host-bus-adapters/sas-9305-24i

Here are 24.

 

Have fun, share the results.