SATA PCI card or port multiplier (internal).

[RimBlock]

Hi,

I am playing with my sample NSC-400 mITX case with 4x hot swap and the possibility of up to 2x 2.5" SATA drives.

As I am looking to run an Atom board in it I need to add some more SATA ports to handle the 6 drives. The two boards I am looking at are the D2700MUD and the D2500CC (dual network ports) but both have PCI slots (oh why do you tease us so Intel). Both boards have mPCIe slots so I am looking at mPCIe -> dual sata cards to add two more and am investigating PCI SATA controllers but with the PCI slots max speed of 133MB/s, putting more than a couple of drives on it is going to heavily impact drive / motherboard throughput.

One thought occurred which was to use port multipliers to double up the motherboard sata or the mPCIe SATA. There is very little I have found that may be of much use though.

I could use the D2800MT with a PCIe slot and dual mPCIe card slots (1xfull and 1xhalf size) but that is another $25 or so on top. I could then add something like the Syba SY-PEX40008 (I have yet to read any reviews). That works out to be about $56 different from the D2500CC but will run all 6 drives.

Another option is using a Supermicro board with 6 sata but that is the previous gen D525.

Suggestions ?

Thanks
RB

 

[wkearney99]

Is there any way to use a regular PCIe card in an mPCIe slot? Then you could use something a SAS adapter and some SATA breakout cables to connect up to 8 drives (or more externally). This would seem smarter than using multiple 2-port mPCIe adapters.

 

[MiniKnight]

mPCIe is more or less a x1 slot I thought. could be wrong

 

[Mike]

There are these risers out there for that purpose. But keep in mind that speed will be severely limited. 1x pcie 1.0 would be 250mb/s if i'm not mistakin' which is not a lot for an 8 port hba, 2.0 would be double that but still not enough.

 

[wkearney99]

There are these risers out there for that purpose. But keep in mind that speed will be severely limited. 1x pcie 1.0 would be 250mb/s if i'm not mistakin' which is not a lot for an 8 port hba, 2.0 would be double that but still not enough.

This diagram was insightful: http://serverfault.com/questions/11633/whats-the-bandwidth-and-form-factor-for-pcie-x1-x4-x8-and-x16

Yes, if you're talking to 8+ drives directly then doing it through a 1x port is going to be less than ideal. It'd be less of a problem if you were dealing with an array controller on the board that was talking to the drives. There you'd at least be getting near single hard drive speeds through a 1x interface. But I've no idea which controllers would work. It'd certainly be an interesting experiment.

 

[Patrick]

Nice diagram but the speed in each direction is a bit dated. Actually a x1 PCIe controller would actually make some sense now with effectively 1GB/s in each direction.

 

[ehorn]

I found this wiki to be a nice, quick reference:

http://en.wikipedia.org/wiki/List_of_device_bit_rates

 

[PaulOlave]

Then you could use something a SAS adapter and some SATA breakout cables to connect up to 8 drives (or more externally). This would seem smarter than using multiple 2-port mPCIe adapters.

 

[RimBlock]

Interesting.

The D2500 / D2700 Atom boards have a mPICe x1 v2 at the best guess. The boards also support either a single or double PCI cards using a 1 -> 2 riser. The tech specs do not detail if the PCI slot is 33 or 66MHz but notes the dual PCI card option requires a riser with compatibility with a 2nd 33MHz clock.

So 2 on-board SATA II + 2 SATA II via mini-PCIe + up to 2x PCI cards.

so;
2x SATA II = 200 MB/s per drive max.
2x SATA II via mPCIe = 200MB/s per drive max.
2, 4 or 8x SATA II via PCI (1 or 2 cards - dual or quad port) = 133MB/s (possibly 266MB/s if 66MHz) / number of drives accessed.

The fact is I am thinking entry level here so not top speed but at least reasonable.

I suspect 4 drives will be possible but 6+ will be difficult and prone to stability issues.

RB