Ming Zhang <mingz@xxxxxxxxxxx> writes: > On Mon, 2005-07-11 at 11:11 -0400, Dan Christensen wrote: >> I was wondering what I should expect in terms of streaming read >> performance when using (software) RAID-5 with four SATA drives. I >> thought I would get a noticeable improvement compared to reads from a >> single device, but that's not the case. I tested this by using dd to >> read 300MB directly from disk partitions /dev/sda7, etc, and also using >> dd to read 300MB directly from the raid device (/dev/md2 in this case). >> I get around 57MB/s from each of the disk partitions that make up the >> raid device, and about 58MB/s from the raid device. On the other >> hand, if I run parallel reads from the component partitions, I get >> 25 to 30MB/s each, so the bus can clearly achieve more than 100MB/s. >> >> [...] >> >> System: >> - Athlon 2500+ >> - kernel 2.6.12.2 (also tried 2.6.11.11) >> - four SATA drives (3 160G, 1 200G); Samsung Spinpoint >> - SiI3114 controller (latency_timer=32 by default; tried 128 too) > > only 1 card? 4 port? try some other brand card and try to use several > cards at the same time. i met some poor cards before. Yes, one 4-port controller. It's on the motherboard. I thought that since I get good throughput doing parallel reads from the four drives (see above) that would eliminate the controller as the bottleneck. Am I wrong? Dan - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
