Help understanding how a RAID card works and expands / connects to backplane

[Marzipan]

question about the RAID adapter AOC-S3008L-L8i
https://www.supermicro.com/en/products/accessories/addon/AOC-S3008L-L8i.php

it has two external ports, which supports 8 internal ports and up to 63 devices, which I assume means SSD / HDD.

that card is installed into this chassis, that has 16x 2.5" bays split between two backplanes with 8 bays each.
https://www.supermicro.com/en/products/system/2U/2029/SYS-2029P-TXRT.cfm

that adapter has it's two ports connected to the backplane for drives 0 thru 7.

too use the other 8 bays, Supermicro support says we need to buy another one of those cards with a couple cables.

why do we need another card when the first one is supposed to support up to 63?

my client is fine with having to buy what we've been told to...but we want to understand why the existing card can't do the job.

 

[moocow]

Not an expert in this field. 8 internal ports supports up to 32 drives (1 port for 4 drives) but the external ports are basically SAS expander hooking up to another box. So the total the controller can handle is up to 63 devices.

 

[gingerbee]

So the controller can handle up to 63 devices but the card only has 2xmini sas to 8 SATA breakout cables. if this is true what the point on listed what the chip can handle. sorry friendly not trying to jump on your thread

or do you just need mini sas to a breakout cable with more than 4 SATA plug ??? or does it need to have SAS expanders ???
I think it's the second one.

don't know if this may help I think

educate me about SAS controller

Can someone educate me about SAS controllers? There are many things I don't understand about SAS controllers and I can't find good answers from the web. Here is one example, Areca ARC-1680ix-8 SAS RAID Controller http://www.pc-pitstop.com/sas_controllers/arc1680ix8.asp PCIe x8, Intel IOP348...

hardforum.com

 

[Marzipan]

ahhh...so from what you're saying, the chip on the board is capable of a lot more than the output they configured the card with.

 

[gingerbee]

That's what I think I just don't know for sure, I don't deal with raid cards much at all. but from what it looks like your right the chip can handle much more but it needs those extra posts that you may get from SAS expander cards. if you look at the parts list at the bottom of the spec page it lists an add-in card for SAS port expansion

I would wait for someone who deals with raid cards on the regular just to be sure.

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this seems to have more info hope it helps, I just wanted to understand more too.

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From what I can see it all depends on if that raid card supports expanders, fingers crossed it does. good luck