i can't show you raw write values, but I can show you raw read values (after dropping the caches): >From dstat, this shows disks sdb, sdc, and sdd values in read (space) write format, with the total on the end. Thus: 70M 0 : 71M 0 : 72M 0 : 213M 0 71M 0 : 70M 0 : 69M 0 : 210M 0 71M 0 : 73M 0 : 74M 0 : 217M 0 shows that I'm getting 70+- MB/s on each disk, combined to 210 to 217MB/s. These are read values. I created a logical volume (50G), dropped the caches again, and issued: dd if=/dev/zero of=/dev/raid/test bs=64k and got from 100 to 150MB/s sustained write speeds. NOTE: this is with a bitmap (internal) Without a bitmap (removed for this test), I get a much more consistent 130-150MB/s. dd reports a mere 70MB/s when complete. When using oflag=direct, I get about 100MB/s combined, with a "reported" speed of 51.9MB/s. Since I'm using 3x drives, my total I/O is going to be about 2x what dd "sees". Does that help? -- Jon -- 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
