[SunRescue] Fiber Channel, was RE: HBA's

[William Janssen]

Re. the info below. Is there any interest in lenghts of fiber? I see
rolls of the stuff (with connectors) in the scrap from time to time.

Bill K7NOM

Christopher Byrne wrote:
> 
> Behalf Of Al Potter
> Sent: Monday, December 04, 2000 08:45
> >HitechCafe has had cheapass FC drives for a while....
> >
> >       http://www.hitechcafe.com/eshop/product.asp?dept%5Fid=7&sku=ST19171FC
> >
> >Other similar good deals are out there....
> >
> >What sort of gear (controller, cabling, etc) is required to get this up and
> >running, and is there an inexpensive controller option for Sparc (SBus,
> PCI)
> >or the PC (PCI)?
> 
> Ayup, like I said Fiber Channel drives are cehap, it's the HBA's and cables
> that really kill you.
> 
> Okay the minimum for a Fiber Channel setup (or fibre channel if you're from
> outside the U.S.) is an FC-AL HBA (Fiber Cahnnel Arbitrated Loop Host Bus
> Adapter). This is essentially a combination of an extremely fast SCSI
> adapter, an ethernet card, and a fiber optic bridge, since you can run
> several different encapsulation layers over fiber channel. Remember FC is
> just the physcal medium, and can be used for many different protocols. FC
> devices are still SCSI, they are just using a serial fiber optic connection
> (2 fibers usually) instead of 68 tiny copper wires.
> 
> In order to have internal drives you need to have an HBA with internal
> ports, or a bridge from the inside of the case to your external ports, which
> I don't recommend. Unfortunately most HBA's only have external ports.
> 
> You then need to decide on a connection standard. There are four or five
> different connectors, but the most common would be SC. You also need to
> decide on single mode or multi mode fiber (this effects your cabling,
> switching, range, etc...). If you are smart you will get an HBA that allows
> you to change modes and connectors through something called a GBIC, which is
> basically a plug in module containing two small lasers, two small laser
> receptors, and the connectors you have chosen.
> 
> Once that is done you need to get cables compatible with your choices. Once
> again with internal drives this may be difficlut since most cabling, and
> most HBA's in fact are made to go from HBA to HBA(loop mode) or HBA to
> switch (fabric mode). While it is tehnically possible to make your own
> cables, I recommed against it. Unless your cable run is very short you need
> to highly polish the ends of the fiber before terminating it with
> connectors, otherwise you get a large amount of refraction, and your data
> can be lost. And premade polished fiber is not cheap, though to be honest
> neither is high quality SCSI cabling.
> 
> In order to connect to multiple devices you need to have either a switch, a
> hub, an MDF (media distribution facility), or you could just have a
> controler with multiple ports and add another fiber. I'm not sure what Sun's
> deal is on their new workstations, but judging from how they handled their
> SCSI cabling in the past they probably just put in a very simple MDF with
> connections to each drive bay.
> 
> Overall fiber channel is actually no more complicated than copper paralell
> SCSI is, but we are much more familiar with copper, and used to it's
> complications. Fiber is a relativley new world to most of us, and it just
> sounds a lot more difficult. But believe me, being able to connect every
> machine in your building to a single storage array with a couple of hundred
> devices all on the same fabric, and never have to worry about cable length
> is a joyful thing.
> 
> Chris Byrne
> =======================================
> The eyes may be the windows on the soul
> But the word is the doorway to the mind
> =======================================
> 
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