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this really is a Dell question but tempted to ask the experts @ serverfault.

choosen a Dell powerconnect 8024 10GbE switch. per the spec sheet this has 10GbaseT ports.

"24x 10GBASE-T (10Gb/1Gb/100Mb) with 4x Combo Ports of SFP+ (10Gb/1Gb) or 10GBASE-T"

the HBA on my storage server has 10G CX4 copper ports

Dell does not sell any cables and this adds to my confusion.

from the picture Dell 8024 seems to have RJ-45 type ports on the front panel? my question: is it a RJ-45 + CX4 cable or CX4 + CX4 cable?

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2 Answers

up vote 4 down vote accepted

There's no such thing as a "10gb Ethernet interface". There are a variety of interfaces and cables, suited to a variety of speeds.

  • 10g base-t is the the old RJ45/Cat6 interface that most people associate with networking
  • SFP+ is what we use at my site - this can be fibre or copper (direct attached) depending on needs. We use copper inside racks and fibre to link to other switch rooms.
  • 10GBASE-CX4 is physically very similar to infiband and I think for a while was the most viable way of delivering 10Gb connections inside a cabinet, but I'm not sure I'd choose it for a new setup these days.

Now as to your question - you seem to be implying you're buying a switch with one type of connection to connect to devices using a different type of connection. This is obviously not going to end well.

You need to speak to Dell (and possibly other suppliers) about something that will support the CX4 connections on your storage server, plus whatever type of connection you propose to use for the rest of the LAN. (It may also turn out cheaper to replace the HBA rather than mix and match). The Dell switch you're currently looking at does not have connections for the CX4 HBA. You can't just put one type of connector at one end of a cable and a different connector on the other end in this kind of situation, there's a bit more going on here than just the type of plug.

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Hi, thanks for the info. Since the HBA cant be changed, can i choose Dell 8024F switch with SFP+ ports? The HBA is 10G-CX4 copper ports. –  John-ZFS Dec 24 '10 at 13:47
    
Well I've got a preference for SFP+ so I can't criticise the choice of a 8024F as such, but that still won't help you connect CX4 ports to it. You need to find something that will support CX4 (plus whatever you want to connect other devices with) or you need to change the HBA. These connections are totally different physically. –  RobM Dec 24 '10 at 13:52
    
Just had a look around for you, and HP do a module for their blade switches that might help. h10010.www1.hp.com/wwpc/ie/en/sm/WF06c/… - would mean getting something like a HP procurve 5406 as your switch, and depending on your port needs this could end up expensive. –  RobM Dec 24 '10 at 14:00
    
thanks a bunch. Since i cant change the switch , the HBA has to be changed. –  John-ZFS Dec 24 '10 at 14:19
    
Not necessarily. See my answer above. –  ewwhite Dec 24 '10 at 17:34
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You can use a CX4->QSFP+ adapter cable to connect the storage system to one of the 4x combo ports on the Dell for under $100.

Here's a link to compatible Amphenol cables.

Note the image in the product description. This will allow you to keep the HBA currently in the storage system and still be compatible with the majority of 10G-capable switches with SFP+ ports.

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hi, thanks for bright idea, seems to save my day and investment. The product is QSFP to CX4, but the ports on my Dell 8024 are SFP+, are they compatible? –  John-ZFS Dec 24 '10 at 17:36
    
Looking again, probably not :( The QSFP is an Infiniband thing. I've used direct-attach SFP+-SFP+ copper cables, but there doesn't seem to be an SFP+-CX4 adapter cable available. –  ewwhite Dec 24 '10 at 18:56
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