Am Sonntag, 19. März 2006 00:42 schrieb Tracy R Reed: > Andrew Lentvorski wrote: > > Yes, and one controller and cable per disk is a *good* thing. > > > > For example, a hot swap failure won't take down the entire chain. A > > terminator failure won't take down the entire chain. A cable ground > > fault won't fry multiple drives. > > That is a very good point which I had not considered before. I am pretty > sure I have seen a device error take down a whole chain. I also very > much like the fact that the small serial ATA cables decrease airflow > blackage much less than the ribbon cables. And when wiring up two drives > on an PATA ribbon cable it always seemed like I had to put an awkward > twist in the cable to make the connectors line up right. Very annoying. > The decreased airflow blockage is very important in a 1u case. I saw a > case in our datacenter the other day that had a ribbon cable laying flat > up against the front of the intake vents of a 1u case. I should probably > have something done about that.
First: SCSI ribbons can be up to 1.8m long IIRC. No problem attaching them with clips. Second: "cable ground error"? I haven't come across such a failure in 11 years. Possibly because I treat equipment well. How common is that? Third: in ATA RAID arrays each drive has it's own cable, master/slave arrangements are technically possible but have a devastating impact on performance. Noticable already on desktop machines, I don't wanna find out the hard way how bad it is on softraid. > Very interesting. Serial-attached SCSI. I hadn't heard of that before > but it makes sense. Why didn't we go to these serial technologies > sooner? I am guessing the signal processing capabilities did not exist. Precisely. You can carry a HF signal only so far. Modern disks are about to saturate a GBE line - 8 wires. Hm, on the other hand... hard disks with 10GB links... yeah, that'd be neat :) > > I have heard for years that SCSI drives get the platters and drive heads > that QA'd higher or some such thing. I have always wondered if that was > true. I am skeptical. But even if SCSI is more reliable it can't be by > that much and my plan is to use the saved money (SATA saves lots of > SCSI) and buy more hot spares. An IBM employee confirmed this right to my face. Seemed honest for a suit. -- -----BEGIN GEEK CODE BLOCK----- Version: 3.12 GCS d--(+)@ s-:+ a- C+++(++++) UL+>++++ P+>++ L+++>++++ E-- W++ N o? K- w--(---) !O M+ V- PS++(+) PE(-) Y++ PGP t++(---)@ 5 X+(++) R+(++) tv--(+)@ b++(+++) DI+++ D G++ e* h>++ r%>* y? ------END GEEK CODE BLOCK------ http://www.stop1984.com http://www.againsttcpa.com -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
