SAS/SATA Networking?

[Argher]

I had this thought today...networking via SAS or SATA as a speedy, short range networking tool akin to firewire's ability to connect computers. SATA in particular is ubiquitous, and offers 3gb/s of bandwidth currently.

I know SAS has SAS extenders, which act somewhat like ethernet switches. I also would think that you could theoretically program a driver for SATA that would enable it to use TCP/IP rather than I/O functions.

Thoughts? Or, if you know of high-bandwidth networking beyond the range of gigabit ethernet, while less expensive than Myrinet or Infiniband, to name two, I'm all ears.

Of course, this is platform-independent. How could this be implemented, on any specific OS or in general?

 

[Modelworks]

The problem would be range.
Once you start pushing 1gb+ on a cable your going to generate all kinds of rf garbage you have to deal with.
optical fills that need without having to worry about distance as much.

SATA could be adapted with a network driver but it would be a lot of work and with other options already proven and working its just not worth the effort.
Its more a "can we or should we" type thing.
It can be done, but looking at all the work involved it probably shouldn't.

 

[Peter]

SATA is a serial incarnation of a specific controller bus, implementation details reaching back to the ISA bus days. On the far end of the cable, you can have nothing but a disk controller.

Abusing SATA physical interface chips for other purposes would be entirely possible - but given the availability of 10 gigabit ethernet chips (Broadcom, Intel, ServerEngines), why bother?

Your next problem will be finding system chipsets that handle this kind of bandwidth to begin with. Your average desktop toy won't.

 

[Argher]

Theoretically, I suppose what I'm really after is negating another of the downsides of gigabit ethernet, which is the latency. The other HPC networking interfaces have substantially lower latency, which I believe would be possible to replicate if you were building this sort of functionality from the ground up.

Part of the appeal of SATA/SAS to me is their future expandability as far as bandwidth - SAS has the intention to reach 12Gbit, for example, which slightly one-ups infiniband 4x and Myrinet 10G, as well as 10gbit ethernet (all of which are quite expensive at the moment). Thus the work done now would pay off in future. In addition, SAS is compatible with SATA, and the link switching of extenders should be usable as a networking switch.

I'm not so worried about range, as ideally I would have very short interconnects for latency, interference and cluster density reasons.

Of course, really what I'm after is a high-bandwidth, low-latency networking solution, undercutting the pricing of current high-end offerings. Anything I'm likely to build will be with off-the-shelf components, more or less, and under 100 cores. Thus the attraction of paying for, say, a gigantic Myrinet switch is somewhat nonexistent.

 

[Steve]

iSCSI, aka SCSI Over IP do anything for you?

Doesn't Fiber Channel have some range to it too?

 

[Argher]

iSCSI is more or less what I'm thinking of in reverse, no? It sends the SCSI data over a tcp/ip interface such as ethernet.

As far as fiber channel.. yes, that could work, if I could find some decent 2gb+ cards and a switch for 'em.

 

[Scarpozzi]

Don't forget you can do NIC teaming and use Etherchannel.