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When reading the specifications for the LSi SAS 9206-16e HBA, it says

Storage Connectivity; Data Transfer Rates
* 16 ports; 6Gb/s SAS 2.1 compliant 

SAS Bandwidth   
* Half Duplex 2400MB/s, x4, 6Gb/s SAS lanes

Port Configurations
* 16 ea, x1 ports (individual drives)
* 4 ea,  x4 wide ports
* 2ea, x8 wide ports

Connectors
* Four (x4) mini-SAS HD external connectors (SFF8644)

So there are 4 physical connectors.

Question

What is the bandwidth for each of the connectors?

I would be temped to say 6Gb/s * 4, but then it mentions the "Port Configurations" and 2ea, 4ea, 16ea, which I don't understand what is.

Does this mean, that the 4 physical connectors are not identical?

Update

I would like to connect an external SuperMicro disk shelf with 45 SATA 7200RPM disks. From what I have heard, then the maximum bandwidth I will be able to get out of such a diskshelf is 24Gb/s. So my interest in this question is do I need 1 or 2 cables?

Sandra
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3 Answers3

5

Looks like you're planning another fun ZFS project, Sandra :)

For some clarity on SAS topology and the different methods of connecting devices, please see my post at: How exactly does a SAS SFF-8087 breakout cable work? + RAID/connection questions

As for the LSI SAS 9206-16e controller you're looking at, the device is very simple.

  • "16e" stands for sixteen external ports. This card is only meant to interface with and external storage controller. It has no ability to link to internal server drives or backplanes.

  • The four ports are SAS SFF-8088 ports. These are 4-lane external SAS ports. Each lane is a 6Gbps link, so you are carrying 4*6Gbps (24Gbps) bandwidth per cable and per port. So for four ports, that's 96Gbps total bandwidth.

The better question is really: what you're planning to connect to this controller?

Most external JBOD enclosures only accept two 4-lane SAS cables... so you'll be oversubscribed, depending on the disk density and storage layout.

Community
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ewwhite
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  • I have now updated the OP =) It is exactly my ZFS NAS I now want to expand with a 45 disk disk shelf =) If it is correct, that I onæy can get 24Gb/s out of a 45 disk shelf, then it would be temped to think that I can just use one cable. Or do you think it is 24Gb/s without overhead so I therefore need two cables? – Sandra Jun 30 '13 at 21:26
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    You'll want two cables. Depends on the external JBOD and whether the expander can accommodate two cables. – ewwhite Jun 30 '13 at 21:42
  • Great! I haven't bought the disk shelf yet, so I can buy any JBOD HBA it should be. I haven't even bought the LSi SAS 9206-16e HBA yet, so even that could change. With 45 disks of 3Gb/s each, would I get better throughput by connecting more than two cables? – Sandra Jul 01 '13 at 10:15
2

The connectors are identical. Each connector has 4 SAS lanes. Each lane supports 6 Gb/s, but the total bandwidth that the chipset can handle over 4 lanes bonded together is 2400 MB/s, which works out to about 18 Gb/s (about 6 Gb/s less that the total available bandwidth).

The port configuration describes how you are allowed to hook up the devices. The physical connectors each carry 4 lanes and the card supports up to 16 lanes total. You can use those lanes as either 16 individual lanes, 4 lanes bonded together, or 8 lanes bonded together. In any of those cases, you will need an appropriate fan-out cable or expander.

Chris S
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longneck
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-1

Reading your post and the link, what I do understand is:

Each port is up to 6GB/s, but the bandwith is 2.4Gb/s per device in a four lanes configuration, which mean a 4ea Configuration.

But which is strange, is the Support for up to 1024 SAS or SATA end devices sentence. I don't really now how they connect 1024 devices on 16 ports Oo or they use replicators.

Dr I
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  • What does 4ea configuration mean? The 1024 devices is if you daisy chain them. – Sandra Jun 28 '13 at 15:28
  • About my understanding, it means that your drives will have 4 access paths, but I'm not sure. – Dr I Jun 28 '13 at 19:44
  • -1 Dude, that says 2.4GBps, not 2.4Gbps. SAS doesn't use replicators, it uses expanders. I don't mean to be offensive but your Answer is chock-full of misinformation and it's clear you don't know what you're talking about. – Chris S Jun 30 '13 at 04:15
  • No you're not offensive, I just said it upper, "ABOUT MY UNDERSTANDING", so you just proved that I misunderstand the tech sheet ;-) About the B vs b Come on dude, everyone understand correctly the point. So thanks for the informations about expander and the lanes :D – Dr I Jun 30 '13 at 10:34