Syba/IO Crest bridge chips

[DougShields]

I was doing some research today, thought I would pass this along.

 

Looking at the SD-PEX40163

• 8 Port SATA III to PCIe 3.0 x1 NON-RAID Expansion Card SD-PEX40163
• Uses Two ASM1064 connected to a ASM1182e PCI-e Bridge

and the SI-PEX40165

• 8 Port SATA III to PCIe 3.0 x1 NON-RAID Expansion Card SI-PEX40165
• Uses Two ASM1064 connected to a ASM1806 PCI-e Bridge

 

The ASM1182e and the ASM1806 are PCIe 2.0 bridge chips, so the description of the card as being PCIe 3.0 x1 is wrong.  The ASM1064 is a PCIe 3.0 chip, but that doesn’t matter once it’s behind the PCIe 2.0 bridge chip.

 

ASM1806

ASM1182e

ASM1064

 

It looks like the 16 port SD-PEX40164 uses Four ASM1064 with an ASM2806 which is PCIe 3.1, but for double the price.

 

I've e-mailed Syba USA to see if they have an explanation, but I don't expect a real answer.

 

Background: This is for legacy spinning rust, the main storage is NVMe, the good slots have NICs in them, so I'm looking at PCIe 3.0 x1 cards for good reason.

[ConnerVT]

Anything that is taking 1 PCIe lane to 8 SATA ports must be using a multiplier.

[DougShields]

On 11/14/2023 at 4:25 PM, ConnerVT said:

Anything that is taking 1 PCIe lane to 8 SATA ports must be using a multiplier.

 

Not necessarily - usually it's a multiplier, but that is not the only possible solution.  A multiplier splits at the SATA level, a bridge splits at the PCIe level.

 

It is effectively the same as having additional controllers.  In this case two ASM1064 controllers which have 4 ports each.  With the obvious limitation that they must split bandwidth.  Some of the LSI SAS HBAs are actually very similar where they plant 2 controllers on 1 card in order to double the port count while also doubling the capacity and cost.

[ChatNoir]

11 hours ago, DougShields said:

Some of the LSI SAS HBAs are actually very similar where they plant 2 controllers on 1 card in order to double the port count while also doubling the capacity and cost.

Which can be fine as long as you double the number of PCIe lanes.

Here, it is still 8 SATA ports on a x1. Unless I made a mistake on my (early morning) math, even HDDs will have their max bandwidth seriously limited.