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On a passive SFF-8639 backplane, with one port per drive, is it possible to connect some of the back side SFF-8643 ports to a SAS HBA and the others to an NVMe card like the Supermicro AOC-SLG3-2E4?

The specific scenario I'm looking at is the upcoming IcyDock MB699VP-B, which is toted as a '4 Bay 2.5" NVMe U.2 SSD' hotswap rack. However, since 12Gbit SAS also uses 8639 and 8643 for drive and board connections, I'm wondering if I can mix drive types in this enclosure, or any non-expander backplane that uses these connections.

PSpacer
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2 Answers2

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The 'IcyDock MB699VP-B' turns U.2 disks into plain vanilla SAS disks, so they can be connected to a suitable SAS-based HBA/RAID controller alongside 'native' SAS disks and treated the same. Seems utterly pointless though as you're throwing away all of the benefits of NVMe (bandwidth, queue numbers and depths) by just converting them to SAS, may as well just buy SAS SSDs to be honest.

By the way this all seems a little 'hackey'/consumer/non-professional, perhaps superuser might be a better place for this kind of question in the future - they build unsupported/unsupportable stacks there all the time.

Chopper3
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  • As far as I know the only thing that is changed is the connector, the protocol being sent over the wire is still NVMe. – PSpacer Feb 28 '18 at 17:58
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The MB699VP-B ports are U.2 ports, so SATA SSDs will not fit in them.

I should note that Chopper3's answer above is incorrect. The MB699VP-B cannot connect to a SAS HBA. Each rear port is PCIe 4x and must be connected to a PCIe or M.2 slot via an adapter such as this: https://www.amazon.com/SFF-8639-Adapter-Mainboard-Intel-SFF-8643/dp/B01D8F9JAK

And yes you still get all of the benefits of NVMe since the drives are still connected to a 4x PCIe bus.

aikilord
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  • 12Gbit SAS drives use the U.2 connector, which are the type of SSDs I'll be using. Regardless, SAS ports are always compatible with SATA drives through STP. – PSpacer Feb 28 '18 at 18:13
  • Looks like I got some bad information, the drives I'm looking at use the regular SFF-8482 connector that all previous versions of SAS have been using. – PSpacer Feb 28 '18 at 20:57