My hard drives magically arrived today. I think they were shipped, um, yesterday. w00t ;-)
Anyway, I plugged in three for a test. I'd previously removed one of the connectors from my cable loop, as it was connected to a drive that was broken anyway. That seemed to go fine.
Then, I decided to add the fourth connector, and things start breaking again. Fortunately, the drives seem to be fine, I just need to fix my cabling. The problem is probably because that the guy who made my connectors gave me cables for them that were made from Category 5 cable. You may have heard of this—it's what most people use for Ethernet cabling these days. Unfortunately, Cat5 cable is designed to carry signals in the range of 125 MHz (Fast Ethernet runs at 125 MHz on the wire, but uses an error-correction code that brings the maximum speed down to 100 Mbit/s). FibreChannel, as I may have mentioned, runs somewhere around ten times that speed.
The least the guy could have done was splurge on some Cat5e...
Anyway, I guess I'll snag a Category 5e or Category 6 Ethernet cable from Best Buy sometime in the not-too-distant future, rip it up, and replace the stuff I currently have. I know that some of the 5e cables there have had stuff like “rated up to 350 MHz!” written on the packaging.
I forget what speed Gigabit Ethernet really runs at, but my brain keeps snapping back to 250 MHz. I'll have to look it up at some point. That seems absurdly low, though.
There are 4 pairs of wires (8 wires total) in a standard Ethernet cable, though most cards only need two pairs (4 wires) to be there. Gigabit Ethernet uses all 4 pairs, and the truly geeky may recall that there was a variant of Fast Ethernet called 100Base-T4 that used 4 pairs (the more common version is 100Base-TX). Using 4 pairs allowed a 100Mbit/s connection on an old Category 3 wire, which couldn't adequately carry the 125MHz Fast Ethernet signal..
Posted by mike at June 7, 2003 04:45 PM | Hardware | TrackBack