Yan Seiner wrote: > Tejun Heo wrote: >> Yan Seiner wrote: >> >>> Sorry for the delayed response. I've installed another controller based >>> on the SiI 3132 chipset. The esata array is the same; I've simply moved >>> the esata cables to the new controller. My observations: >>> >>> 1. The JMicron 20360/20363 AHCI Controller (rev 03) controller is far, >>> far slower. hdparm clocks it at 20 mb/sec and a raid check takes about >>> 15 hours. >>> >> >> Hmm... That's probably due to lack of FIS based switching support. >> The hardware (20360/3) can't do it and ahci doesn't support it yet >> either. So, only commands to one drive can be in flight at any given >> moment which is usually pretty bad for RAID. >> > So is there hope that FIS switching will make it into the driver or is > this a hardware limitation? I have some time (months if not a year or > two) before I really start to populate my external disk pack. (I have > 20 slots with 4 - 5 port multipliers.) 20360/3 don't support them in hardware but there are controllers which do and ahci driver will be updated to support them. >> As said above, if you're running RAID on top of it, command based >> switching will hurt bad. And 110Mb/s is about the limit of sil3132. >> > I'm OK with the speed of the sil controller. I'm concerned about the > slow speed of the jmicron controller - it's about 1/3 to 1/5 as fast. Yeah, that's the difference coming from FIS and command based switching. > OK, thanks. I'll check the drive jumpers and see about setting the > lower speed. No, you don't have to do that. You can just use libata.force parameter. ie. if the JMB one is ATA host 3, you can say libata.force=3:1.5Gbps. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
