HPE EVA Storage

HBA - "Single Port" vs "Dual Port"

 
Deeptanshu Gupta
Occasional Advisor

HBA - "Single Port" vs "Dual Port"

We have to connect our DL580 G7 with SAN . I concern is should I procure 2 Single port HBA or 1 Dual port HBA. My understanding was to have 2 Single port HBA as 1 dual port HBA will be single point of failure. I was recommended by my vendor to procure 2 x HP StorageWorks FC1142SR 4Gb PCIe Host Bus Adapter(AE311A). this card has 2 ports but its single channel. I am confused now.

Will there be any configuration limitation to have 2 Single port HBA rather than 1 dual port HBA ? or will 2 single port HBA works the same way a dual port HBA

And why do we have 2 port in HP StorageWorks FC1142SR 4Gb PCIe Host Bus Adapter(AE311A) when its only single channel?

Please help
15 REPLIES 15

Re: HBA - "Single Port" vs "Dual Port"

Dual port HBA and single port HBA has been designed based on the situations or I can say based on the availability of IO slots you can use.

Server like HP DL580 having 6 IO slots so you can use single port HBAs but HP DL380 having 3 IO slots where you need to use dual port HBA so that you can use other IO slots for NIC and all.

Now two single port HBA is always good over one dual-port HBA because of redundancy.

Single port HBA spreads IO acress multiple PCI slots so gives better resilience. Each adapter having it's own PCI bus so throughput is better.(Again depends on PCI technology)

There are several issues at hand here:

1> How many slots you have for HBAs. If you only have 1, go with Dual/Quad Port.
2> How many PCI Busses you have. If you have only 1 buss, go with Single/Dual/Quad Port in multiple slots. Why? If a slot fails you are still up. However if the bus fails you are down. If you have multiple busses, place the HBAs on different busses.

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Deeptanshu Gupta
Occasional Advisor

Re: HBA - "Single Port" vs "Dual Port"

And why do we have 2 port in HP StorageWorks FC1142SR 4Gb PCIe Host Bus Adapter(AE311A) when its only single channel?

Re: HBA - "Single Port" vs "Dual Port"

As per my understanding cost is the main factor here.

For customer who are not much aware of the technology they are going for single channel 2 port HBA because of low cost but who are all aware of technology they will go for dual channel 2 port HBA even though high cost.

For official link please refer below,
http://h18000.www1.hp.com/products/quickspecs/11941_div/11941_div.PDF

http://h18000.www1.hp.com/products/servers/proliantstorage/adapters/singlechannel/benefits.html


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Johan Guldmyr
Honored Contributor

Re: HBA - "Single Port" vs "Dual Port"

One fibre in the fibre cable is for sending and one for receiving. That's why the single port actually has two smaller ports "inside it".
Deeptanshu Gupta
Occasional Advisor

Re: HBA - "Single Port" vs "Dual Port"

thanks for the reply.

my concern is not cost. i just want to understand the difference between 2 port single channel or 2 port dual channel.

i dont want to have this card as a snigle point of faliure. i understand that 2 single port single channel cards are better than 1 dual port dual channel card. but my confusion is dual port single channel card.

i hope you are getting my point
Johan Guldmyr
Honored Contributor
Deeptanshu Gupta
Occasional Advisor

Re: HBA - "Single Port" vs "Dual Port"

Re: HBA - "Single Port" vs "Dual Port"

With Single channel single port HBA one WWNN and one WWPN.

With single channel dual port HBA one WWNN and two WWPN.

With dual channel dual port HBA two WWNN and two WWPN.

So in case of zoning these matters.

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Uwe Zessin
Honored Contributor

Re: HBA - "Single Port" vs "Dual Port"

Looks like somebody has put a wrong picture on the page that Deeptanshu Gupta gave the link to.
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