On Thu, 2002-06-13 at 22:23, natecars at real-time.com wrote: > On 13 Jun 2002, Mike Hicks wrote: > > I've seen cheap FC drives floating around, but I suspect there must be > > a hidden cost somewhere.. Don't most of those drives use SCA > > backplanes? That can't be cheap. [snip] > Controller is expensive. They aren't SCA, they are some sorta interface I > haven't actually seen in person.. :) I've done some looking around. It still appears that most drives use an SCA connector, though it's a 40-pin SCA-2, as opposed to 80-pin SCA(-2?) that SCSI backplanes generally use. Fibre Channel is just a two-wire interface, but since it has a loop topology, you need a transmit and a receive pair on any device. Most FC disks appear to handle dual-loop fibre channel, so they have four pairs, two on each loop. The SCA connector carries power and some other miscellaneous stuff. It'd probably be less common, but most FC disks tend to go into hot-plug arrays, which ends up being a lot less error prone when using a connector like that, since all connections can generally be broken simultaneously. I found a pinout description [http://www.hitachi.com/documents/Storage/opstore/dk319h-18fc,0.pdf (page 28)], and apparently it isn't too complicated to do, as I found a website that seems to be a guy who makes homebuilt FC connectors in his garage ("homebuilt" and "fibre channel" should probably not go in the same sentence ;-) [http://sca40.homelinux.net/products.html] Of course, for connecting between other devices, it looks like there are a couple of different connectors. DB9s are apparently common (it uses the outside four pins for the TX/RX pairs), and there are some HSSDC (don't ask me what that is, just look at the above page). At any rate, if that stuff is any good, you can get connection to 4 drives for $200-250. That seems to make it competitive with the FireWire idea I had, though there's a tradeoff. IDE drives are still cheaper per gigabyte, but getting Fibre Channel would leave a lot more breathing room for I/O bandwidth.. -- _ _ _ _ _ ___ _ _ _ ___ _ _ __ I'm afraid of Americans / \/ \(_)| ' // ._\ / - \(_)/ ./| ' /(__ \_||_/|_||_|_\\___/ \_-_/|_|\__\|_|_\ __) [ Mike Hicks | http://umn.edu/~hick0088/ | mailto:hick0088 at tc.umn.edu ] -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 232 bytes Desc: This is a digitally signed message part Url : http://shadowknight.real-time.com/pipermail/tclug-list/attachments/20020614/e61cde93/attachment.pgp